fix(web): browser game UX pass — shake feedback, timer, stock count, HUD

- game.js fully rewritten: correct coordinate system (PAD baked into
  PILE_ORIGIN), undo driven by undo_stack_len, flashIllegal shake with
  --card-tx CSS variable, game timer, stock count HUD, URL seed persist,
  foundation suit hints, auto-complete step loop
- game.html: adds hud-timer, hud-stock, win-time elements
- game.css: @keyframes illegal-shake, .slot-hint, overflow-x on main
- solitaire_wasm: adds undo_stack_len to GameSnapshot

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_server/web/game.html

@@ -15,6 +15,8 @@
         <div class="hud-center">
             <span id="hud-score">Score: 0</span>
             <span id="hud-moves">Moves: 0</span>
+            <span id="hud-timer">0:00</span>
+            <span id="hud-stock">Stock: 24</span>
         </div>
         <div class="hud-right">
             <button id="btn-undo" title="Undo (Z)">↩ Undo</button>
@@ -34,6 +36,7 @@
             <div class="win-title">You Won!</div>
             <div id="win-score" class="win-score"></div>
             <div id="win-moves" class="win-detail"></div>
+            <div id="win-time" class="win-detail"></div>
             <button id="btn-win-new">Play Again ↺</button>
         </div>
     </div>