help: add relay, context menu, find/replace, assets, super-buckets docs; fix flaky tests

Updates help screen with all undocumented features. Fixes F1 blocked
by input suppression filter (allow function keys). Stabilizes card-join
tests with poll loop instead of fixed sleep.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/js/modules/shortcuts.js

@@ -114,8 +114,8 @@ document.addEventListener('keydown', (e) => {
         if (!matched) continue;
 
         // Suppress non-modifier shortcuts when focus is in an editable field
-        // (except Escape which should always close overlays)
-        if (inEditable && !s.ctrl && !s.alt && !s.match && e.key !== 'Escape') continue;
+        // (allow Escape and function keys like F1 through)
+        if (inEditable && !s.ctrl && !s.alt && !s.match && e.key !== 'Escape' && !e.key.startsWith('F')) continue;
 
         // Guard
         if (s.guard && !s.guard()) continue;