fix(ui): offline in-game — usable dictionary check + hide (not disable) resign/chat

Two fixes from contour testing of the offline-in-game UX:

- The dictionary word check was unusable offline (Check button disabled) when the
  panel was reached while already offline: CheckScreen fetched the variant + pinned
  version over the network in onMount, which fails offline, leaving the default
  variant so input sanitising stripped every letter. Seed both from the cached game
  (present once the board has opened) so the input and the on-device dawg fallback
  work without a round-trip; the network refresh still runs when online and on a
  cold deep-link.
- The resign and chat controls were only functionally disabled (chat) or not gated
  at all (resign) offline, so they still looked active. Hide both while offline,
  matching the frozen social controls.

Tests: the in-game offline e2e now asserts the drawer action icons are hidden (not
disabled); a new e2e guards the offline dictionary flow. Docs updated.

ui/src/game/CheckScreen.svelte

@@ -8,6 +8,7 @@
   import { alphabetLetters } from '../lib/alphabet';
   import { canCheckWord, dictionaryLookupUrl, sanitizeCheckWord } from '../lib/checkword';
   import { onExternalLinkClick } from '../lib/links';
+  import { getCachedGame } from '../lib/gamecache';
   import type { Variant } from '../lib/model';
 
   // Word-check on its own screen: unlimited dictionary lookups, each with a
@@ -25,15 +26,24 @@
   const checked = new Map<string, boolean>();
 
   onMount(async () => {
+    // Seed the variant + pinned version from the cached game first (present once the board has opened,
+    // and preloaded for ongoing games): an online game's dictionary must keep working while offline,
+    // where the gameState call below cannot run. The variant's alphabet is already cached from opening
+    // the board, so input sanitising and the offline dawg fallback work off the seed alone.
+    const cached = getCachedGame(id)?.view.game;
+    if (cached) {
+      variant = cached.variant;
+      dictVersion = cached.dictVersion;
+    }
     try {
-      // Include the alphabet so input sanitising + the check accept the variant's letters. Routed
-      // through gameSource so an offline (local) game resolves its state from the device, not the
-      // network.
+      // Refresh over the network (and cache the alphabet on a cold deep-link that skipped the board).
       const st = await gameSource(id).gameState(id, true);
       variant = st.game.variant;
       dictVersion = st.game.dictVersion;
     } catch (e) {
-      handleError(e);
+      // Offline or a transient failure: the cache seed already set variant + version, so only surface
+      // an error when there was nothing cached to fall back to.
+      if (!cached) handleError(e);
     }
   });
 

ui/src/game/Game.svelte

@@ -1607,6 +1607,10 @@
       {:else if view.game.hotseat}
         <!-- Hotseat resign is a host (referee) action, not self-serve; keep the slot empty. -->
         <span aria-hidden="true"></span>
+      {:else if !netReady}
+        <!-- Offline: resigning needs the server, so hide the control (like the frozen social controls);
+             an empty slot keeps the header's space-between layout. -->
+        <span aria-hidden="true"></span>
       {:else}
         <button class="hicon" onclick={onResignClick} disabled={waitingForOpponent} aria-label={t('game.dropGame')}>🏁</button>
       {/if}
@@ -1615,8 +1619,8 @@
            chat, so its hub is Dictionary-only (CommsHub), and once finished the dictionary closes too
            — so drop the entry only when a local game is finished; an active local game keeps it for
            the Dictionary. An online game always keeps it (chat outlives the game). -->
-      {#if !(gameOver && (view.game.vsAi || view.game.hotseat))}
-        <button class="hicon" disabled={!netReady} onclick={() => navigate(`/game/${id}/chat`)} aria-label={t('game.chat')}>
+      {#if netReady && !(gameOver && (view.game.vsAi || view.game.hotseat))}
+        <button class="hicon" onclick={() => navigate(`/game/${id}/chat`)} aria-label={t('game.chat')}>
           {#key chatBlink}<span class="chat-ico" class:blink={chatBlink > 0 && !app.reduceMotion}>💬</span>{/key}
         </button>
       {/if}