Phase 1 fixes:
- lobby.js: guest waits 2.5s before entering game (gives host time to detect)
- challenge.js: validate match_id exists before navigating to lobby
- match-session.js: remove visibilitychange listener on destroy (memory leak fix)
- match-session.js: only fire onConnectionRestored after actual disconnection
- net.js: handle non-JSON server responses gracefully (nginx 502 pages etc)
- result.js: pass actual timeControl to rematch instead of hardcoded rapid_10_0
- Remove dead chess/logic/live.js and ludo/logic/live.js (unused)

Fixes WTF #15, #19, #23, #24, #35, #37, #54, #150
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>