feat(telegram): harden channel reliability with retries and error diagnostics

src/config/schema.ts

@@ -3,7 +3,7 @@ import { z } from 'zod';
 const telegramSchema = z.object({
   bot_token: z.string().min(1, 'Bot token is required'),
   allowed_chat_ids: z.array(z.number()).min(1, 'At least one chat ID required'),
-  require_mention: z.boolean().default(true),
+  require_mention: z.boolean().default(false),
 });
 
 const tailscaleSchema = z.object({