Honor UntilChanged in sync; let SearchSelect own its disabled look

Follow-ups on the add-form fixes:

- syncSelectInputUntilChanged now actually stops mirroring once the user edits
  the target (the "UntilChanged" contract). The old focus-based stop was a
  no-op (wrong removeEventListener reference), so live sync kept clobbering a
  manually-edited Sort name. Track dirty targets in a Set keyed by syncData
  index; programmatic writes don't fire "input", so only real user edits mark a
  target dirty. Drops the dead focus listener.

- SearchSelect now greys itself when disabled, via has-[:disabled]: utilities on
  its container class — the visible "box" is the wrapper <div>, so disabling the
  transparent inner input alone left it looking active. The component owns its
  disabled appearance; callers only toggle the inner control's `disabled`.

- Document the composite-widget disabling approach in CLAUDE.md and the
  SearchSelect docstring.

Extends the e2e tests: sync drops after a manual Sort name edit; disabled
related-game wrapper computes opacity 0.5 (and 1 when re-enabled).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

games/static/base.css

@@ -3430,6 +3430,16 @@
       outline-style: none;
     }
   }
+  .has-\[\:disabled\]\:cursor-not-allowed {
+    &:has(*:is(:disabled)) {
+      cursor: not-allowed;
+    }
+  }
+  .has-\[\:disabled\]\:opacity-50 {
+    &:has(*:is(:disabled)) {
+      opacity: 50%;
+    }
+  }
   .data-\[search-select-highlighted\]\:bg-brand {
     &[data-search-select-highlighted] {
       background-color: var(--color-brand);