Disable unavailable subreddits after Reddit 404

src/config/index.ts

@@ -9,6 +9,7 @@ dotenv.config();
 
 export const SubredditConfigSchema = z.object({
   name: z.string(),
+  enabled: z.boolean().default(true),
   type: z.enum(['image', 'chat']).default('image'),
   weight: z.number().positive().optional(),
   tone: z.enum(TONE_KEYS).default('default'),