refactor(core): optimize state management and component rendering performance

Improve application stability and performance by optimizing Zustand store usage, implementing memoization patterns, and introducing persistent authentication.

- **State Management**:
  - Refactor Zustand selectors to use `useShallow` and `getState()` to prevent unnecessary re-renders and infinite loops in hooks.
  - Implement `persist` middleware for `authStore` to maintain user sessions across restarts.
  - Introduce `buildStateCached` in `themeStore` to reduce redundant theme object computations.
- **Performance & Rendering**:
  - Implement `useMemo` for stable object/array references in `ImageGallery` and list components to prevent expensive re-renders.
  - Replace inline arrow functions with `useCallback` in complex screens like `ChatScreen` and `MessageListScreen`.
  - Optimize `FlashList` usage by providing stable `key` and `extraData` props.
- **Architecture**:
  - Decouple unread count fetching by introducing `useUnreadCountQuery` (React Query) for better caching and synchronization.
  - Add `useChannels` hook to centralize channel data fetching.
  - Refine `SessionGate` logic to allow immediate rendering of authenticated users while verifying in the background.

src/stores/settings/themeStore.ts

@@ -34,6 +34,24 @@ function buildState(
   };
 }
 
+let _cachedKey = '';
+let _cachedState: ReturnType<typeof buildState>;
+
+function buildStateCached(
+  preference: ThemePreference,
+  systemScheme: ResolvedScheme
+): {
+  resolvedScheme: ResolvedScheme;
+  colors: AppColors;
+  paperTheme: MD3Theme;
+} {
+  const key = `${preference}:${systemScheme}`;
+  if (_cachedKey === key && _cachedState) return _cachedState;
+  _cachedKey = key;
+  _cachedState = buildState(preference, systemScheme);
+  return _cachedState;
+}
+
 type ThemeState = {
   preference: ThemePreference;
   systemScheme: ResolvedScheme;
@@ -58,14 +76,14 @@ export const useThemeStore = create<ThemeState>((set, get) => ({
   preference: 'system',
   systemScheme: initialSystemScheme,
   hydrated: false,
-  ...buildState('system', initialSystemScheme),
+  ...buildStateCached('system', initialSystemScheme),
 
   setSystemScheme: (systemScheme) => {
     const { preference, systemScheme: cur } = get();
     if (cur === systemScheme) return;
     set({
       systemScheme,
-      ...buildState(preference, systemScheme),
+      ...buildStateCached(preference, systemScheme),
     });
   },
 
@@ -78,7 +96,7 @@ export const useThemeStore = create<ThemeState>((set, get) => ({
     const { systemScheme } = get();
     set({
       preference,
-      ...buildState(preference, systemScheme),
+      ...buildStateCached(preference, systemScheme),
     });
   },
 
@@ -97,7 +115,7 @@ export const useThemeStore = create<ThemeState>((set, get) => ({
       preference,
       hydrated: true,
       systemScheme,
-      ...buildState(preference, systemScheme),
+      ...buildStateCached(preference, systemScheme),
     });
   },
 }));