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/base.css

@@ -124,6 +124,17 @@ body {
     display: none !important;
 }
 
+:focus-visible {
+    outline: 2px solid var(--color-accent);
+    outline-offset: 2px;
+}
+
+button:focus:not(:focus-visible),
+input:focus:not(:focus-visible),
+select:focus:not(:focus-visible) {
+    outline: none;
+}
+
 @media (prefers-reduced-motion: reduce) {
     *,
     *::before,
@@ -132,4 +143,8 @@ body {
         animation-iteration-count: 1 !important;
         transition-duration: 0.01ms !important;
     }
+
+    html {
+        scroll-behavior: auto !important;
+    }
 }