Restore Arena Campaign scoring progression (#110)

[themuffinator]

What changed

• Saved and transactionally zeroed si_warmupReadyPercentage whenever Arena disables ready-up.
• Saved the player's g_matchProfile, forced Arena through the casual authored-CVar adapter, and explicitly refreshed that import for every card.
• Restored both settings after the match.
• Added a focused contract for the rule-boundary invariants and updated release-completion notes.

Root cause

Arena set si_useReady=false but left the clean-profile ready threshold at 0.51. The typed casual adapter therefore produced disabled readiness with a 5100-basis-point threshold. Validation rejected field 4/reason 17, and every WARMUP→COUNTDOWN transition was refused. The intro still unlocked combat, but the server remained in infinite WARMUP, where scoring is intentionally suppressed.

A second lifecycle defect was adjacent: the multiplayer object survives map shutdown, so two consecutive DM-backed campaign cards could reuse the first card's committed rule snapshot unless the profile selector was explicitly refreshed.

Validation

• python tools/tests/validation_hardening.py
• python tools/tests/arena_campaign.py
• documentation, charset, Python compile, and diff checks
• Windows x64 client compile and link
• Windowed, no-input, engine-screenshot runtime against stock assets:
  • match 1 imported 8 frags / 6 minutes, reached a finite 5:43 clock, and recorded a forced self-kill as score -1
  • after disconnect/restoration, match 2 imported its own 12 frags / 7 minutes, reached a finite 6:43 clock, and recorded score -1
  • an archived competitive profile was restored after both matches
  • zero competitive rules rejected diagnostics and no fatal engine diagnostics

Fixes #110

[themuffinator]

Final hosted validation for 712e4a3: 21 checks passed, 4 failed, 0 pending. Commit Validation and ARM64 Cross Build passed completely, including ASan/UBSan and both universal2 assembly/package/smoke jobs. The four red macOS Push Verification jobs exactly reproduce the renderer-default-safety baseline on main and are unrelated to the Arena campaign rule change.