Blur gallery images by default, sync progress UI, and add chat/monitor tests

- Blur NSFW media gallery images until hover/reveal
- Surface chat sync progress in the dashboard header
- Extend chat service, cache, and monitor with delta-media handling
- Add tests for chat cooldown, delta media, and monitor flows

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/web/types.ts

@@ -42,4 +42,8 @@ export interface RuntimeConfig {
   browser: {
     dryRun: boolean;
   };
+  reddit: {
+    prioritizeRecentPosts: boolean;
+    recentWindowMinutes: number;
+  };
 }