v0.5.1 - repo polish for Windows + Codex

Windows + Codex focused repo polish release.

Highlights:

• Added clear GitHub metadata: description, homepage, and searchable topics
• Added community files: SECURITY.md, SUPPORT.md, issue templates, and PR template
• Rewrote CONTRIBUTING.md for .codex/skills/gstack and Windows-first workflows
• Cleaned up generated SKILL.md formatting so setup snippets render as readable Bash
• Aligned VERSION and package.json to 0.5.1

Recommended Windows auth flow:

1. browse login-session headed https://target-site.com
2. Sign in manually once
3. browse login-session headless
4. Reuse normal browse commands with the saved login state

Known limitation:

• Direct cookie import from default Chrome or Edge profiles may still fail on Windows when app-bound cookie encryption is enabled. In that case, use the persistent login-session flow instead.