fix: mobile toolbar height — icons no longer overflow

- .mobile-toolbar: 56px → 64px + padding 4px (was 0)
- .main-layout padding-bottom: 56px → 64px
- .mt-btn: height auto + min-height 48px (was fixed 48px)
- .mt-btn: gap 3px (was 2px), padding 4px (was 2px)

frontend/style.css

@@ -7357,22 +7357,22 @@ body.popup-mode .content-area {
     bottom: 0;
     left: 0;
     right: 0;
-    height: 56px;
+    height: 64px;
     background: var(--bg-secondary);
     border-top: 1px solid var(--border);
     z-index: 900;
     align-items: center;
     justify-content: space-around;
-    padding: 0 4px;
-    padding-bottom: env(safe-area-inset-bottom, 0);
+    padding: 4px 4px;
+    padding-bottom: calc(4px + env(safe-area-inset-bottom, 0));
     -webkit-backdrop-filter: blur(12px);
     backdrop-filter: blur(12px);
   }
 
   /* Push content up to avoid toolbar overlap */
   .main-layout {
-    padding-bottom: 56px;
-    padding-bottom: calc(56px + env(safe-area-inset-bottom, 0));
+    padding-bottom: 64px;
+    padding-bottom: calc(64px + env(safe-area-inset-bottom, 0));
   }
   .editor-modal.active ~ .main-layout {
     padding-bottom: 0;
@@ -7419,10 +7419,11 @@ body.popup-mode .content-area {
     flex-direction: column;
     align-items: center;
     justify-content: center;
-    gap: 2px;
+    gap: 3px;
     flex: 1;
-    height: 48px;
-    padding: 2px 4px;
+    height: auto;
+    min-height: 48px;
+    padding: 4px 4px;
     border: none;
     border-radius: 8px;
     background: transparent;