fix: pill toggle layout — icons absolutely positioned, thumb slides over

Icons are now at fixed positions inside the pill (globe left,
hard-drive right) with absolute positioning. The thumb slides
between them. The active icon is the one NOT covered by the thumb:
- Off: thumb left (covers globe), hard-drive visible
- On: thumb right (covers hard-drive), globe visible
Icons fade with opacity transitions. Thumb changes from white
(off) to black (on) to contrast with the yellow active background.

frontend/index.css

@@ -44,14 +44,12 @@ p {
     position: relative;
     display: flex;
     align-items: center;
-    width: 56px;
-    height: 28px;
-    border-radius: 14px;
+    width: 52px;
+    height: 26px;
+    border-radius: 13px;
     background: var(--yj-bg-overlay, rgba(255, 255, 255, 0.1));
     cursor: pointer;
     flex-shrink: 0;
-    padding: 0 4px;
-    justify-content: space-between;
     transition: background 0.2s ease;
 }
 
@@ -61,18 +59,19 @@ p {
 
 .mode-toggle-thumb {
     position: absolute;
-    top: 3px;
-    left: 3px;
+    top: 2px;
+    left: 2px;
     width: 22px;
     height: 22px;
     border-radius: 50%;
     background: var(--yj-text-primary, #fff);
-    transition: left 0.2s ease;
+    transition: left 0.2s ease, background 0.2s ease;
     z-index: 1;
 }
 
 .mode-toggle.active .mode-toggle-thumb {
-    left: 31px;
+    left: 28px;
+    background: #000;
 }
 
 .mode-toggle.active {
@@ -80,25 +79,33 @@ p {
 }
 
 .mode-icon {
-    font-size: 13px;
+    position: absolute;
+    top: 50%;
+    transform: translateY(-50%);
+    font-size: 12px;
     z-index: 2;
-    transition: color 0.2s ease;
+    transition: opacity 0.2s ease;
+    pointer-events: none;
 }
 
 .mode-icon-globe {
-    color: var(--yj-text-primary, #fff);
+    left: 7px;
+    color: #000;
+    opacity: 0;
 }
 
 .mode-icon-local {
+    right: 7px;
     color: var(--yj-text-secondary, #b3b3b3);
+    opacity: 1;
 }
 
 .mode-toggle.active .mode-icon-globe {
-    color: rgba(0, 0, 0, 0.3);
+    opacity: 1;
 }
 
 .mode-toggle.active .mode-icon-local {
-    color: #000;
+    opacity: 0;
 }
 
 ul {