release: prepare 0.3.1 store build

[sjungwon03]

Summary

Prepares the next production release: OpenScene 0.3.1, iOS build 2, and Android versionCode 2. This is required because 0.3.0 is already tagged and build 1 has already been uploaded to both stores.

Closes #194

Validation

• Release metadata JSON parsed.
• npm test -- tests/releaseWorkflow.test.ts
• git diff --check passed.
• npm run typecheck (CI pending)
• npm test (CI pending)
• npm run build (CI pending)

Checklist

• This pull request targets dev.
• I created or linked a GitHub issue for this change.
• I used a Conventional Commit message.
• Tests are not directly applicable to a version-only release change; CI is running.
• I updated release documentation.
• I did not include secrets, private media, private file paths, credentials, or security exploit material.

Notes for reviewers

Promotion of this version from dev to main will invoke the main-release workflow, which uploads iOS to App Store Connect and publishes Android to the Play production track.

[sjungwon03-ai]

Approved. Version bump from 0.3.0 to 0.3.1 across app.json, package files, and docs is clean and matches the release title. No code changes or issues found.