feat(admin): Stack minigame tab icon (TowerBlock bar asset)

Thai: ไอคอนแท็บ Minigame-3 + CSS tab-heading-icon--stack-tab
English: /Game/img/TowerBlock/admin-tab-minigame-3.png, contain in 52×20 box.
Co-authored-by: Cursor <cursoragent@cursor.com>

www/html/Admin/admin.css

@@ -525,6 +525,13 @@ legend {
   height: 22px;
 }
 
+/* Minigame-3 Stack — สินทรัพย์แท่งแนวนอนยาว (object-fit contain ในกล่องนี้) */
+.tab-heading-icon--stack-tab {
+  width: auto;
+  max-width: 52px;
+  height: 20px;
+}
+
 .tab-label {
   font-size: 0.88rem;
   font-weight: 600;

www/html/Admin/index.html

@@ -70,7 +70,7 @@
         <button type="button" class="tab" data-tab="map-editor" role="tab" id="tab-map-editor" aria-controls="tab-panel-map-editor"><span class="tab-label">Editor</span><span class="tab-desc">แผนที่ฉาก</span></button>
         <button type="button" class="tab" data-tab="quiz" role="tab" id="tab-quiz" aria-controls="tab-panel-quiz"><span class="tab-heading-row"><img class="tab-heading-icon" src="/Game/img/QUESTION/admin-tab-minigame-1.png" width="22" height="22" alt="" decoding="async"><span class="tab-label">Minigame-1-จริงหรือไม่</span></span><span class="tab-desc" aria-hidden="true"></span></button>
         <button type="button" class="tab" data-tab="game-timing" role="tab" id="tab-game-timing" aria-controls="tab-panel-game-timing"><span class="tab-heading-row"><img class="tab-heading-icon" src="/Game/img/gauntlet-assets/gauntlet-dd51baed17270995.png" width="22" height="22" alt="" decoding="async"><span class="tab-label">Minigame-2-วิ่งหลบสิ่งกีดขวาง</span></span><span class="tab-desc" aria-hidden="true"></span></button>
-        <button type="button" class="tab" data-tab="stack-game" role="tab" id="tab-stack-game" aria-controls="tab-panel-stack-game"><span class="tab-label">Minigame-3-Tower block</span><span class="tab-desc" aria-hidden="true"></span></button>
+        <button type="button" class="tab" data-tab="stack-game" role="tab" id="tab-stack-game" aria-controls="tab-panel-stack-game"><span class="tab-heading-row"><img class="tab-heading-icon tab-heading-icon--stack-tab" src="/Game/img/TowerBlock/admin-tab-minigame-3.png" width="48" height="18" alt="" decoding="async"><span class="tab-label">Minigame-3-Tower block</span></span><span class="tab-desc" aria-hidden="true"></span></button>
         <button type="button" class="tab" data-tab="quiz-carry" role="tab" id="tab-quiz-carry" aria-controls="tab-panel-quiz-carry"><span class="tab-heading-row"><img class="tab-heading-icon tab-heading-icon--wide" src="/Game/img/quiz-carry/admin-tab-minigame-4.png" width="32" height="22" alt="" decoding="async"><span class="tab-label">Minigame-4-คำศัพท์ในกระบวนการยุติธรรม</span></span><span class="tab-desc" aria-hidden="true"></span></button>
         <button type="button" class="tab" data-tab="quiz-battle" role="tab" id="tab-quiz-battle" aria-controls="tab-panel-quiz-battle"><span class="tab-label">Quiz Battle</span><span class="tab-desc">โดม · A B C · หมวด</span></button>
         <button type="button" class="tab" data-tab="jump-survive" role="tab" id="tab-jump-survive" aria-controls="tab-panel-jump-survive"><span class="tab-heading-row"><img class="tab-heading-icon" src="/Game/img/Jumper/admin-tab-minigame-5.png" width="22" height="22" alt="" decoding="async"><span class="tab-label">Minigame-5-กระโดดขึ้นแท่น</span></span><span class="tab-desc" aria-hidden="true"></span></button>