fix: add --surface-subtle token, restore info grouping, and apply theme-aware favorite color

- Add --surface-subtle (oklch 3% opacity) to replace rgba(0,0,0,0.03)
- Fix info items, creator-info, civitai-view, modal-send-btn, header-actions
  to use --surface-subtle instead of --surface-hover
- Keep true hover states on --surface-hover
- Use light #d4a017 / dark #ffc107 for --favorite-color based on theme
- Replace hardcoded #ffc107 and #d4a017 with var(--favorite-color)

static/css/layout.css

@@ -83,11 +83,13 @@
     box-shadow: var(--shadow-xs);
 }
 
-.control-group button:hover {
+.control-group button:hover,
+.control-group button:focus-visible {
     border-color: var(--lora-accent);
     background: var(--bg-color);
     transform: translateY(-1px);
     box-shadow: var(--shadow-lg);
+    outline: none;
 }
 
 .control-group button:active {
@@ -100,7 +102,8 @@
     transition: opacity 0.2s ease;
 }
 
-.control-group button:hover i {
+.control-group button:hover i,
+.control-group button:focus-visible i {
     opacity: 1;
 }
 
@@ -131,7 +134,7 @@
 
 .control-group button.favorite-filter i {
     margin-right: 4px;
-    color: #ffc107;
+    color: var(--favorite-color);
 }
 
 .control-group button.update-filter i {