docs(web,readme): taste pass — fix stale refs, tighten design rhythm

Polish fixes (12):
- INSTALL.md: drop duplicate code block; doc CODEWHALE_VERSION canonical
  env var; fix example mirror URLs /DeepSeek-TUI/ → /CodeWhale/; remove
  stale "Once npm publication resumes" conditional
- footer.tsx: fix Gitee mirror URL deepseek-tui → CodeWhale
- globals.css: update seal CSS shadows from old cream rgba(244,241,232)
  to paper white rgba(255,255,255)
- web/README.md: update palette description cream #FAF6EE → white #FFFFFF
- nav.tsx: fix zh-only date strip (第…期) and API label (在线) — now
  "Edition …" / "API · Online" in en mode
- page.tsx: hardcoded v0.8.56 → dynamic facts.version
- README.md: merge duplicate Contributing sections
- README.ja-JP/vi: parenthesize untranslated Chinese thank-you blurbs

Design rhythm (9):
- ThinkingTrace section: py-16→py-20, bg-paper-deep, hairlines for reveal
- Judgment stack: py-16→py-12; middle cell bg-paper-deep for ABA rhythm
- Maintainer loop: py-16→py-14; step numbers grow 01→04
- How it works: py-16→py-12
- Join in closer: py-16→py-20 (dark section breathes)
- Ticker: LIVE label shrunk to annotation weight

README.md

@@ -189,12 +189,6 @@ CodeWhale exists because of the people who use it, break it, and fix it.
 - **Every contributor** — the full per-PR record lives in
   [docs/CONTRIBUTORS.md](docs/CONTRIBUTORS.md). Thank you.
 
-## Contributing
-
-See [CONTRIBUTING.md](CONTRIBUTING.md). Pull requests welcome — check the
-[open issues](https://github.com/Hmbown/CodeWhale/issues) for good first
-contributions.
-
 ## License
 
 [MIT](LICENSE)