config: agent_panel block (enabled/surfaces/min_quality/daily budget)

New optional config.json block for the upcoming LLM agent-panel feature:
enabled, telegram, dashboard (per-surface toggles), min_quality,
max_panels_per_day, reuse_ttl_seconds. Absent block → {} → feature dark.
Validation mirrors the deepseek block. Module 23 opened with parse +
reject tests.

Claude-Session: https://claude.ai/code/session_01SisdfkxnXNL9iZsXxN3T15

config.json.example

@@ -40,5 +40,13 @@
     "timeout_seconds": 12,
     "daily_request_cap": 500
   },
+  "agent_panel": {
+    "enabled": false,
+    "telegram": true,
+    "dashboard": false,
+    "min_quality": "B",
+    "max_panels_per_day": 20,
+    "reuse_ttl_seconds": 3600
+  },
   "log_level": "INFO"
 }