fix(agent-office): get_running_loop + pytrends timeout + UA 수정

- asyncio.get_event_loop() → asyncio.get_running_loop() (python 3.10+ 권장)
- TrendReq에 timeout=(5, 15) 추가 (connect, read timeout)
- User-Agent에서 'bot' 제거: 표준 Chrome UA로 변경

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

agent-office/app/youtube_researcher.py

@@ -82,7 +82,7 @@ async def fetch_google_trends(keywords: List[str], countries: List[str]) -> List
 
     def _sync_fetch(kw: str) -> List[Dict[str, Any]]:
         try:
-            pt = TrendReq(hl="en-US", tz=0)
+            pt = TrendReq(hl="en-US", tz=0, timeout=(5, 15))
             pt.build_payload([kw], timeframe="now 7-d")
             df = pt.interest_over_time()
             if df.empty or kw not in df.columns:
@@ -96,7 +96,7 @@ async def fetch_google_trends(keywords: List[str], countries: List[str]) -> List
         except Exception:
             return []
 
-    loop = asyncio.get_event_loop()
+    loop = asyncio.get_running_loop()
     results = []
     for kw in keywords[:5]:
         rows = await loop.run_in_executor(None, _sync_fetch, kw)
@@ -109,7 +109,7 @@ async def fetch_billboard_top20() -> List[Dict[str, Any]]:
     """Billboard Hot 100 스크래핑 — 상위 20위."""
     async with httpx.AsyncClient(
         timeout=10.0,
-        headers={"User-Agent": "Mozilla/5.0 (compatible; music-research-bot/1.0)"},
+        headers={"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"},
         follow_redirects=True,
     ) as client:
         try: