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/PLAN.md

@@ -49,7 +49,7 @@ The emulator-backed prototype is now at `/reference.html`. The default applicati
 
 ## In progress: native battles
 
-The battle core, ROM tables, encounter hooks, battle UI and whiteout hooks are present. Unit tests cover wins, escape, loss, experience and move learning; reference tests compare damage and type effectiveness. Full browser battle flows, capture, Route 29 scripts and the opening quest remain unverified or unfinished.
+The battle core, ROM tables, encounter hooks, battle UI and whiteout hooks are present. Unit tests cover wins, escape, loss, experience and move learning; reference tests compare damage and type effectiveness. Browser tests drive a test-only wild encounter through the real UI: victory with level-up and move learning, escape, whiteout, keyboard and on-screen D-pad menu navigation, mid-battle backup restore, and rollback of unsupported effects. Capture, switching, items in battle, Route 29 scripts and the opening quest remain unfinished.
 
 This is still not a complete new game. Playable battles, party/bag/Pokégear menus, story progression beyond the lab, NPC roaming, decorations, animated terrain, surfing, entering routes and audio remain unfinished. Save slots, a Johto/Kanto atlas, Pokédex records, online Link, friends and real-world steps come later.