chore: prepare CacheVis-RV public showcase release

[Yucheng-art]

Summary

Prepare the sanitized CacheVis-RV repository for a future public showcase release.

This pull request adds presentation, repository-safety, verification, and visitor-facing materials without modifying simulator behavior, application logic, or tests.

Included

• English and Simplified Chinese README files
• Six verified screenshots and a 1280×640 social preview
• Source-available copyright notice
• PySide6 third-party notice
• Security guidance
• Changelog and public-showcase release notes
• Windows PowerShell launch and test scripts
• Windows Python 3.12 GitHub Actions workflow
• Structured bug-report template

Verification

• 720 automated tests passed locally
• Skip 0
• Qt offscreen integration smoke passed
• Real GUI startup smoke passed
• Windows clean-copy installation passed
• Installation from a path containing spaces passed
• 8 Available Labs / 0 Coming Soon
• Old personal commit email removed from reachable public-candidate history
• Approved local workspace paths removed from reachable public-candidate history
• No credentials, private keys, tokens, PDFs, virtual environments, build products, or local output files detected

Scope

This pull request does not modify:

• src/
• tests/
• simulator behavior
• GUI behavior
• requirements
• version metadata
• existing milestone tags

Copyright model

The repository is intended to be publicly viewable for portfolio review, educational evaluation, and demonstration.

No standard open-source license is included. Copyright remains reserved by the author. Third-party dependencies remain subject to their respective licenses.

Release status

• Repository remains Private
• Draft PR only
• No v3.0.0 tag
• No GitHub Release
• No visibility change
• Final publication requires separate approval

Review checklist

• Remote CI passes
• English README approved
• Chinese README approved
• Screenshots approved
• Social preview approved
• Quick Start approved
• Copyright wording approved
• Public history exposure approved
• Final release authorization received