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>

src/ui/styles.css

@@ -448,6 +448,10 @@ dialog h2 {
 .battle-menu button:disabled {
   opacity: 0.5;
 }
+.battle-menu button.battle-selected {
+  outline: 2px solid currentColor;
+  outline-offset: -4px;
+}
 .battle-menu button small {
   display: block;
   font-size: 0.75rem;
@@ -806,7 +810,9 @@ dialog dd {
   .global-bar {
     min-height: 76px;
     grid-template-columns: auto 1fr;
-    grid-template-areas: "play status" "notice save";
+    /* The notice gets its own row: in the button's auto column, a long
+       notice would widen it and crush the status text. */
+    grid-template-areas: "play status" "notice notice" "save save";
     gap: 3px 9px;
   }
   .save-status {