feat(agent-office): YouTubeResearchAgent + 스케줄러 + /youtube/research API

- db.py: youtube_research_jobs 테이블 추가 + CRUD 3종 (add/update/get_latest)
- agents/youtube.py: YouTubeResearchAgent 신규 구현 (on_schedule/on_command/on_approval/_run_research/send_weekly_report)
- agents/__init__.py: YouTubeResearchAgent 등록
- scheduler.py: youtube_research(매일 09:00) + youtube_weekly_report(월 08:00) cron 추가
- main.py: POST /api/agent-office/youtube/research + GET /api/agent-office/youtube/research/status 엔드포인트 추가

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent-office/app/main.py

@@ -4,7 +4,7 @@ from fastapi import FastAPI, HTTPException, WebSocket, WebSocketDisconnect
 from fastapi.middleware.cors import CORSMiddleware
 
 from .config import CORS_ALLOW_ORIGINS
-from .db import init_db, get_all_agents, get_agent_config, update_agent_config, get_agent_tasks, get_pending_approvals, get_task, get_logs, get_activity_feed
+from .db import init_db, get_all_agents, get_agent_config, update_agent_config, get_agent_tasks, get_pending_approvals, get_task, get_logs, get_activity_feed, get_latest_youtube_research_job
 from .models import CommandRequest, ApprovalRequest, AgentConfigUpdate
 from .websocket_manager import ws_manager
 from .agents import init_agents, get_agent, get_all_agent_states, AGENT_REGISTRY
@@ -199,3 +199,29 @@ async def realestate_notify(body: RealestateNotifyBody):
         from fastapi import HTTPException
         raise HTTPException(status_code=503, detail="RealestateAgent not initialized")
     return await agent.on_new_matches(body.matches)
+
+
+# --- YouTube Research Agent Endpoints ---
+
+class YouTubeResearchBody(BaseModel):
+    countries: List[str] = []
+
+
+@app.post("/api/agent-office/youtube/research")
+async def trigger_youtube_research(body: YouTubeResearchBody = None):
+    agent = AGENT_REGISTRY.get("youtube")
+    if not agent:
+        raise HTTPException(status_code=503, detail="YouTubeResearchAgent 없음")
+    params = {}
+    if body and body.countries:
+        params["countries"] = body.countries
+    result = await agent.on_command("research", params)
+    return result
+
+
+@app.get("/api/agent-office/youtube/research/status")
+def youtube_research_status():
+    job = get_latest_youtube_research_job()
+    if not job:
+        return {"status": "never_run"}
+    return job