Improve GitHub visibility and contributor onboarding

.github/ISSUE_TEMPLATE/bug.yml

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+name: Bug report
+description: Report a reproducible problem in an experience or its source.
+title: "[Bug]: "
+labels:
+  - bug
+body:
+  - type: markdown
+    attributes:
+      value: Thanks for helping improve Mint Playground. Please keep security reports private as described in SECURITY.md.
+  - type: input
+    id: experience
+    attributes:
+      label: Experience slug
+      description: The directory name or live-demo slug, such as vanguard-protocol.
+      placeholder: vanguard-protocol
+    validations:
+      required: true
+  - type: textarea
+    id: problem
+    attributes:
+      label: What happened?
+      description: Describe the behavior and what you expected instead.
+    validations:
+      required: true
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Reproduction steps
+      placeholder: |
+        1. Open …
+        2. Select …
+        3. Observe …
+    validations:
+      required: true
+  - type: input
+    id: environment
+    attributes:
+      label: Browser and device
+      placeholder: Chrome 140 on macOS 16, or Safari on iPhone 18
+    validations:
+      required: true
+  - type: textarea
+    id: evidence
+    attributes:
+      label: Screenshots, recordings, or console output
+      description: Remove tokens, personal data, and other sensitive information before posting.
+  - type: checkboxes
+    id: checks
+    attributes:
+      label: Checks
+      options:
+        - label: I searched existing issues for this problem.
+          required: true
+        - label: This is not a security vulnerability.
+          required: true

.github/ISSUE_TEMPLATE/config.yml

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+blank_issues_enabled: false
+contact_links:
+  - name: Mint MCP documentation
+    url: https://mcp.mint.gg/docs
+    about: Get help installing or using Mint MCP.
+  - name: Play the experiences
+    url: https://play.mint.gg
+    about: Confirm whether a problem also appears in the deployed experience.

.github/ISSUE_TEMPLATE/experience-request.yml

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+name: Experience request
+description: Suggest a 3D experience or reusable pattern for a future Playground drop.
+title: "[Experience]: "
+labels:
+  - enhancement
+body:
+  - type: textarea
+    id: concept
+    attributes:
+      label: Concept
+      description: What should someone be able to do, and why is it valuable as an open-source reference?
+    validations:
+      required: true
+  - type: dropdown
+    id: category
+    attributes:
+      label: Category
+      options:
+        - Browser game
+        - Product or commerce
+        - Data visualization or education
+        - Creative or editorial
+        - World or simulation
+        - Reusable Three.js pattern
+    validations:
+      required: true
+  - type: textarea
+    id: learning
+    attributes:
+      label: What should developers learn from it?
+      description: List the interaction, rendering, architecture, or performance patterns it would demonstrate.
+    validations:
+      required: true
+  - type: textarea
+    id: references
+    attributes:
+      label: References
+      description: Link to relevant open-source projects or original visual references. Do not attach unlicensed media.
+  - type: checkboxes
+    id: rights
+    attributes:
+      label: Rights check
+      options:
+        - label: The proposal does not depend on third-party characters, brands, or media that Mint lacks permission to publish.
+          required: true

.github/PULL_REQUEST_TEMPLATE.md

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+## What changed
+
+<!-- Describe the user-visible result and why it is useful. -->
+
+## Experience
+
+<!-- Name the affected experience slug, or write "repository-wide". -->
+
+## Verification
+
+- [ ] `pnpm validate:catalog`
+- [ ] The affected experience builds successfully
+- [ ] Relevant tests pass
+- [ ] I checked keyboard, touch, and reduced-motion behavior where applicable
+- [ ] I included before-and-after captures for visual changes
+
+## Contribution checks
+
+- [ ] This change is focused and does not reformat unrelated files
+- [ ] I have permission to publish all contributed code and media
+- [ ] No credentials, production data, or downloaded Mint CDN assets are included

.github/release.yml

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+changelog:
+  exclude:
+    labels:
+      - skip-changelog
+  categories:
+    - title: New experiences
+      labels:
+        - new-experience
+    - title: Improvements and fixes
+      labels:
+        - enhancement
+        - bug
+    - title: Documentation
+      labels:
+        - documentation
+    - title: Dependency updates
+      labels:
+        - dependencies
+    - title: Other changes
+      labels:
+        - "*"

.github/workflows/validate.yml

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+name: Validate catalog
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+concurrency:
+  group: validate-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  catalog:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+      - name: Validate experience metadata and links
+        run: node scripts/validate-catalog.mjs
+      - name: Verify the experience launcher catalog
+        run: node scripts/play.mjs --list

CODE_OF_CONDUCT.md

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+# Contributor Covenant Code of Conduct
+
+## Our pledge
+
+We pledge to make participation in this project a harassment-free experience
+for everyone, regardless of age, body size, visible or invisible disability,
+ethnicity, sex characteristics, gender identity and expression, level of
+experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our standards
+
+Examples of behavior that contributes to a positive environment include:
+
+- Demonstrating empathy and kindness toward other people.
+- Respecting differing opinions, viewpoints, and experiences.
+- Giving and gracefully accepting constructive feedback.
+- Accepting responsibility and apologizing to those affected by our mistakes.
+- Focusing on what is best for the overall community.
+
+Examples of unacceptable behavior include harassment, trolling, insulting or
+derogatory comments, publishing others' private information, and other conduct
+which could reasonably be considered inappropriate in a professional setting.
+
+## Enforcement
+
+Project maintainers are responsible for clarifying and enforcing these
+standards. They may remove, edit, or reject comments, commits, code, issues, and
+other contributions that do not align with this Code of Conduct.
+
+Report abusive, harassing, or otherwise unacceptable behavior privately through
+the contact options at [mint.gg](https://mint.gg). All reports will be reviewed
+and investigated promptly and fairly. Maintainers will respect the privacy and
+security of reporters.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.1.
+
+[homepage]: https://www.contributor-covenant.org/version/2/1/code_of_conduct.html

CONTRIBUTING.md

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+# Contributing to Mint Playground
+
+Thanks for helping make these open-source 3D experiences easier to learn from,
+run, and reuse.
+
+## Good contributions
+
+The most useful contributions are focused and easy to review:
+
+- Fix a reproducible bug in one experience.
+- Improve keyboard, touch, screen-reader, or reduced-motion support.
+- Improve runtime performance or asset-loading behavior with measurements.
+- Add tests for an existing system.
+- Clarify setup instructions or explain a reusable Three.js pattern.
+- Report a broken demo, source link, or catalog entry.
+
+New experiences are generally published through Mint's release pipeline. Before
+building one for this repository, open an experience request so the maintainers
+can confirm its scope and publication path.
+
+## Before you start
+
+Search existing issues and pull requests first. For a substantial change, open
+an issue describing the user problem and proposed approach before investing in
+implementation. Issues labeled [`good first issue`](https://github.com/mintdotgg/mint-playground/labels/good%20first%20issue)
+are intentionally small and should include enough context to begin.
+
+Only contribute code and media you have permission to publish. Do not commit
+credentials, production data, runtime assets downloaded from Mint CDN, or
+third-party media without a compatible license and attribution. The curated
+social cards under `.github/assets/experiences` are the intentional exception.
+
+## Local setup
+
+This repository uses Node.js 20 or newer and the pnpm version pinned in
+`package.json`.
+
+```bash
+corepack enable
+pnpm install --filter ./experiences/vanguard-protocol
+pnpm play vanguard-protocol
+```
+
+Replace `vanguard-protocol` with any slug printed by `pnpm play --list`.
+
+## Validate your change
+
+Always validate the catalog and build the experience you changed:
+
+```bash
+pnpm validate:catalog
+pnpm --filter ./experiences/vanguard-protocol build
+```
+
+Run experience-specific tests when its `package.json` defines a `test` script.
+Use `pnpm build` only when you need to verify the entire workspace.
+
+## Pull requests
+
+- Keep a pull request focused on one experience or one repository-wide concern.
+- Explain the user-visible result and how you verified it.
+- Include before-and-after captures for visual changes.
+- Preserve each experience's existing framework and style unless the issue
+  explicitly calls for a migration.
+- Update `experience.json` and the root catalog when metadata or URLs change.
+- Do not reformat unrelated files.
+
+By contributing, you agree that your contribution will be licensed under the
+repository's [MIT License](LICENSE).