feat: apply trans-pride gradient theme across UI elements

- Add global CSS classes for trans gradient styling (btn-trans-gradient,
  input-trans-focus, icon-trans-hover)
- Update all primary action buttons to use trans gradient
- Add trans-pride glow effect to character panel based on state
- Update StatusBar icon buttons with trans gradient hover
- Update chat input focus border with trans gradient glow
- Update stop button to use trans gradient

src/lib/components/ConfigSidebar.svelte

@@ -386,7 +386,7 @@
         <button
           onclick={addCustomTool}
           disabled={!newToolName.trim()}
-          class="px-3 py-1.5 text-sm bg-[var(--accent-primary)] hover:bg-[var(--accent-secondary)] text-white rounded-lg transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
+          class="btn-trans-gradient px-3 py-1.5 text-sm rounded-lg"
         >
           Add
         </button>
@@ -569,7 +569,7 @@
       <button
         onclick={handleSave}
         disabled={isSaving}
-        class="w-full py-3 bg-[var(--accent-primary)] hover:bg-[var(--accent-secondary)] text-white font-medium rounded-lg transition-colors disabled:opacity-50"
+        class="btn-trans-gradient w-full py-3 font-medium rounded-lg"
       >
         {isSaving ? "Saving..." : "Save Settings"}
       </button>