feat: add image optimization and settings page

- Add persistent disk cache for processed images
- Optimize image processing with short-circuit and quality settings
- Add WebP lossy encoding with configurable quality
- Add settings API endpoints (GET/POST /settings, cache management)
- Add database table for app configuration
- Add /settings page in backoffice for image/cache/limits config
- Add cache stats and clear functionality
- Update navigation with settings link

apps/backoffice/app/settings/page.tsx

@@ -0,0 +1,20 @@
+import { getSettings, getCacheStats } from "../../lib/api";
+import SettingsPage from "./SettingsPage";
+
+export const dynamic = "force-dynamic";
+
+export default async function SettingsPageWrapper() {
+  const settings = await getSettings().catch(() => ({
+    image_processing: { format: "webp", quality: 85, filter: "lanczos3", max_width: 2160 },
+    cache: { enabled: true, directory: "/tmp/stripstream-image-cache", max_size_mb: 10000 },
+    limits: { concurrent_renders: 4, timeout_seconds: 12, rate_limit_per_second: 120 }
+  }));
+
+  const cacheStats = await getCacheStats().catch(() => ({
+    total_size_mb: 0,
+    file_count: 0,
+    directory: "/tmp/stripstream-image-cache"
+  }));
+
+  return <SettingsPage initialSettings={settings} initialCacheStats={cacheStats} />;
+}