Add grid item size setting and UI

Introduce a persistent gridItemSize user setting (1-10) across the app. Updates include: types (UserSettings.gridItemSize), API mappings (grid_item_size in ApiSettingsItem, CreateSettingsInput, convertApiToSettings, convertSettingsToApi), default setting values, and the App handler (handleGridItemSizeChange) to save changes. UI additions: slider control in SettingsView, slider and value in BrowseView (with syncing to incoming API settings), passing the prop and change callback from App, and a mapping from slider values to responsive Tailwind grid column classes so the grid layout adapts to the chosen size. Also added syncing of itemsPerPage in BrowseView and CastView with API-loaded settings.

src/App.tsx

@@ -103,6 +103,7 @@ function AppContent() {
       const baseSettings = settings || {
         enabledCategories: prev,
         itemsPerPage: 20,
+        gridItemSize: 5,
         defaultView: 'grid',
         showAdultContent: false,
         autoPlayTrailers: false,
@@ -172,6 +173,28 @@ function AppContent() {
     }
   };
 
+  const handleGridItemSizeChange = async (size: number) => {
+    const baseSettings = settings || {
+      enabledCategories: enabledCategories,
+      itemsPerPage: 20,
+      gridItemSize: 5,
+      defaultView: 'grid',
+      showAdultContent: false,
+      autoPlayTrailers: false,
+      language: 'en',
+      theme: 'system',
+    };
+    const updatedSettings: UserSettings = {
+      ...baseSettings,
+      gridItemSize: size,
+    };
+    updateSettings(updatedSettings).then(saved => {
+      if (saved) {
+        setSettings(saved);
+      }
+    });
+  };
+
   const allStaff = useMemo(() => {
     const staff: Staff[] = [];
     // Use API data if available, otherwise fall back to mock data
@@ -295,6 +318,8 @@ function AppContent() {
                 onMediaClick={handleMediaClick} 
                 activeCategory={activeCategory}
                 itemsPerPage={settings?.itemsPerPage}
+                gridItemSize={settings?.gridItemSize}
+                onGridItemSizeChange={handleGridItemSizeChange}
               />
             } />
             <Route path="/media/:id" element={