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/config/index.ts

@@ -25,6 +25,8 @@ export const ConfigSchema = z.object({
     userAgent: z.string().default('RedditBot/1.0'),
     targetGenders: z.array(z.enum(['male', 'female', 'other', 'unknown'])).default(['female']),
     filterSellers: z.boolean().default(true),
+    prioritizeRecentPosts: z.boolean().default(false),
+    recentWindowMinutes: z.number().positive().default(60),
     sellerKeywords: z
       .array(z.string())
       .default([