feat: add popover to confirm abandon

assets/styles/app.css

@@ -631,6 +631,78 @@ body {
     background: #fef2f2;
 }
 
+.abandon-wrapper {
+    position: relative;
+}
+
+.abandon-popover {
+    display: none;
+    position: absolute;
+    top: calc(100% + 8px);
+    left: 50%;
+    transform: translateX(-50%);
+    background: var(--surface);
+    border: 1px solid var(--border);
+    border-radius: var(--radius-md);
+    padding: 14px 16px;
+    box-shadow: 0 4px 16px var(--shadow-warm);
+    z-index: 100;
+    white-space: nowrap;
+}
+
+.abandon-popover.open {
+    display: block;
+}
+
+.abandon-popover-text {
+    margin: 0 0 10px;
+    font-size: 13px;
+    font-weight: 500;
+    color: var(--text);
+    text-align: center;
+}
+
+.abandon-popover-actions {
+    display: flex;
+    gap: 8px;
+    justify-content: center;
+}
+
+.btn-abandon-confirm {
+    padding: 6px 14px;
+    background: #dc2626;
+    color: #fff;
+    border: none;
+    border-radius: 100px;
+    font-family: 'Inter', sans-serif;
+    font-size: 12px;
+    font-weight: 600;
+    cursor: pointer;
+    transition: background 0.15s;
+}
+
+.btn-abandon-confirm:hover {
+    background: #b91c1c;
+}
+
+.btn-abandon-cancel {
+    padding: 6px 14px;
+    background: none;
+    color: var(--text);
+    border: 1.5px solid var(--border);
+    border-radius: 100px;
+    font-family: 'Inter', sans-serif;
+    font-size: 12px;
+    font-weight: 600;
+    cursor: pointer;
+    transition: border-color 0.15s, background 0.15s;
+}
+
+.btn-abandon-cancel:hover {
+    background: var(--surface-hover, #f5f5f5);
+    border-color: var(--text);
+}
+
 .game-start-container {
     display: flex;
     flex-direction: column;