Remove system theme, keep light/dark/neon only

frontend/src/lib/types.ts

@@ -1,4 +1,4 @@
-export type Theme = 'light' | 'dark' | 'system' | 'neon';
+export type Theme = 'light' | 'dark' | 'neon';
 
 /** Lifecycle of the NIP-46 remote signer. */
 export type SignerPhase = 'stopped' | 'connecting' | 'connected';

frontend/src/screens/SettingsScreen.tsx

@@ -104,12 +104,11 @@ export function SettingsScreen() {
               >
                 <option value="light">Light</option>
                 <option value="dark">Dark</option>
-                <option value="system">System</option>
                 <option value="neon">Neon</option>
               </select>
               <p className="hint">
-                “System” follows your desktop's light or dark preference. “Neon” is a pure-black
-                theme with pink and purple accents.
+                “Light” and “Dark” follow your manual selection. “Neon” is a pure-black theme with
+                pink and purple accents.
               </p>
             </div>
           </div>

frontend/src/state/AppProvider.tsx

@@ -335,16 +335,13 @@ export function useApp(): AppContextValue {
   return context;
 }
 
-/** Apply the requested theme (respecting system preference for `system`). */
+/** Apply the requested theme. */
 export function applyTheme(theme: Theme): void {
   if (theme === 'neon') {
     document.documentElement.dataset.theme = 'neon';
     return;
   }
-  const prefersDark =
-    theme === 'dark' ||
-    (theme === 'system' && window.matchMedia('(prefers-color-scheme: dark)').matches);
-  document.documentElement.dataset.theme = prefersDark ? 'dark' : 'light';
+  document.documentElement.dataset.theme = theme;
 }
 
 /** Keep the document theme in sync with settings, watching system changes. */

frontend/src/test/FeedScreen.test.tsx

@@ -24,7 +24,7 @@ describe('FeedScreen', () => {
 
   it('disable relays shows an empty state that can navigate to relays', async () => {
     const settings = {
-      theme: 'system' as const,
+      theme: 'light' as const,
       confirm_before_publish: true,
       shorten_npub: true,
       relays: [

frontend/src/test/apiMock.ts

@@ -25,7 +25,7 @@ export function makeState(overrides?: Partial<AppState>): AppState {
     is_active: false,
   };
   const settings: Settings = {
-    theme: 'system',
+    theme: 'light',
     confirm_before_publish: true,
     shorten_npub: true,
     relays: [