Integrate battles with the overworld UI and validate browser flows

- Drive wild battles through the real UI in Chromium and WebKit using a
  test-only encounter fixture: victory with level-up, escape, whiteout,
  mid-battle backup restore and unsupported-effect rollback.
- Add keyboard and on-screen D-pad navigation for battle menus.
- Accept pending stat experience in saves (awarded without CalcMonStats).
- Commit whiteout healing, money loss and destination callbacks together;
  aborted scripts restore state and map.
- Give long notices their own status-bar row on narrow screens.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/ARCHITECTURE.md

@@ -48,4 +48,4 @@ Asset caches and the ROM reader remain in memory for lazy extraction. Neither RO
 
 The native viewport follows its available CSS dimensions and draws additional world tiles at a bounded pixel resolution. Beyond a map's edge it draws the connected map with the current tileset, as the original connection strips do, and the border block elsewhere. Resizing also redraws paused sessions. The local minimap caches terrain from the loaded map and updates its marker from the same world position used by the player; the Map tab shares that view. It is a current-area map, not a full region atlas. Leaving Game pauses the session and releases held input; returning requires explicit play. The reference player retains its own fixed-screen styling.
 
-`game/battle` now holds the native battle core and ROM-backed battle tables. Its unit and damage/type reference tests do not yet establish the full overworld-to-battle browser flow. Introduce future modules with working features: `game/audio`, then `features/link` and `features/walking`. Party and bag models live in `game/party`; scripts change them only on their draft state. Rules must not import UI/browser modules. Transports and step providers must not write directly into world state.
+`game/battle` now holds the native battle core and ROM-backed battle tables. Browser tests cover the overworld-to-battle flow using a test-only encounter fixture; no production map has encounters enabled yet. Introduce future modules with working features: `game/audio`, then `features/link` and `features/walking`. Party and bag models live in `game/party`; scripts change them only on their draft state. Rules must not import UI/browser modules. Transports and step providers must not write directly into world state.