arcade 0.6.0: a landing page at play.<base>/ instead of the 302

[dmccoystephenson]

Summary

https://play.danielstephenson.dev/ is changed from a 302 to the portal into a real landing page (arcade 0.6.0).

• src/arcade/landing.py renders a small self-contained HTML page from the registry on each request: every game by title, linked to https://<slug>.play.<base>/ (a game with nothing deployed is listed as "Coming soon", unlinked), and a prominent Browse all games → danielstephenson.dev/play link to ARCADE_LANDING_URL.
• No script, no external stylesheet/font/image; Content-Security-Policy: default-src 'none'; style-src 'unsafe-inline'; … enforces it. Light/dark via prefers-color-scheme, phone-first layout, Cache-Control: public, max-age=60, titles HTML-escaped.
• ARCADE_LANDING_MODE = page (default) or redirect (the old 302 to ARCADE_LANDING_URL); any other value refuses to start. The API is unchanged.
• Version 0.6.0, CHANGELOG and README updated.

Verification

• python3 -m pytest (3.8): 127 passed, including new tests/test_landing.py and landing/redirect/HEAD/registry-reload tests in tests/test_server.py.
• The rendered page was loaded in Chromium (Playwright) at desktop 1366 and iPhone 13, light and dark: no horizontal overflow, no console errors, no request beyond the document itself.

The gateway pin is not bumped here.

drafted by Claude on behalf of Daniel Stephenson

🤖 Generated with Claude Code

https://claude.ai/code/session_0116e9DMUhtNXM5bHUdMhDAn