feat: Agent Office — AI 에이전트 가상 오피스 (#2)

## Summary
- 2D 픽셀아트 가상 오피스에서 AI 에이전트(Stock, Music)가 실제 작업 수행
- FastAPI + WebSocket 실시간 상태 동기화 + 텔레그램 봇 양방향 알림/승인
- BaseAgent FSM (idle/working/waiting/reporting/break), 서비스 프록시 패턴
- Docker Compose 서비스 (port 18900) + Nginx WebSocket 프록시

## Changes (13 commits)
- Backend scaffold: config, db, models, Dockerfile
- WebSocket manager + Service proxy
- BaseAgent FSM + StockAgent + MusicAgent
- Telegram bot + Scheduler
- FastAPI main (REST + WS endpoints)
- Infrastructure: docker-compose + nginx
- Code review fixes: HTTPException, async polling, input validation

Reviewed-on: #2

agent-office/app/service_proxy.py

@@ -0,0 +1,34 @@
+import httpx
+from typing import Any, Dict, List, Optional
+
+from .config import STOCK_LAB_URL, MUSIC_LAB_URL
+
+_client = httpx.AsyncClient(timeout=30.0)
+
+async def fetch_stock_news(limit: int = 10, category: str = None) -> List[Dict[str, Any]]:
+    params = {"limit": limit}
+    if category:
+        params["category"] = category
+    resp = await _client.get(f"{STOCK_LAB_URL}/api/stock/news", params=params)
+    resp.raise_for_status()
+    return resp.json()
+
+async def fetch_stock_indices() -> Dict[str, Any]:
+    resp = await _client.get(f"{STOCK_LAB_URL}/api/stock/indices")
+    resp.raise_for_status()
+    return resp.json()
+
+async def generate_music(payload: dict) -> Dict[str, Any]:
+    resp = await _client.post(f"{MUSIC_LAB_URL}/api/music/generate", json=payload)
+    resp.raise_for_status()
+    return resp.json()
+
+async def get_music_status(task_id: str) -> Dict[str, Any]:
+    resp = await _client.get(f"{MUSIC_LAB_URL}/api/music/status/{task_id}")
+    resp.raise_for_status()
+    return resp.json()
+
+async def get_music_credits() -> Dict[str, Any]:
+    resp = await _client.get(f"{MUSIC_LAB_URL}/api/music/credits")
+    resp.raise_for_status()
+    return resp.json()