Add thinking box UI and fix async event loop errors

- Show thinking progress in a separate animated box above chatbot
  (🤔 사고 중... while streaming, 💭 사고 완료 when answer starts)
- Fix ValueError: add missing 5th yield value (thinking_box) to all
  respond() yield statements
- Fix [Reset] and other sync handlers: replace asyncio.get_event_loop()
  .run_until_complete() with asyncio.run() for AnyIO thread compatibility

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

app.py

@@ -95,23 +95,20 @@ async def tts_speak(text: str) -> str | None:
 
 async def respond(message, history, show_thinking, user_id, use_tts, run_ids):
     if not message.strip():
-        yield history, "", None, run_ids
+        yield history, "", None, run_ids, gr.update()
         return
 
     history = list(history)
     run_ids = list(run_ids)
     history.append({"role": "user", "content": message})
     history.append({"role": "assistant", "content": ""})
-    yield history, "", None, run_ids
+    yield history, "", None, run_ids, gr.update(value="", visible=False)
 
     collected_run_id: str | None = None
     tts_text = ""       # 순수 답변만 누적 (TTS용)
     thinking_acc = ""   # 사고 과정 누적
     thinking_active = False
 
-    # 사고 과정 박스 초기화
-    yield history, "", None, run_ids, gr.update(value="", visible=False)
-
     try:
         async for token, run_id in api_client.chat(message, user_id, show_thinking):
             if run_id is not None:
@@ -171,9 +168,7 @@ def handle_feedback(like_data: gr.LikeData, history, run_ids, user_id):
     rating = 1 if like_data.liked else -1
 
     try:
-        asyncio.get_event_loop().run_until_complete(
-            api_client.save_feedback(user_id, user_msg, asst_msg, rating, run_id)
-        )
+        asyncio.run(api_client.save_feedback(user_id, user_msg, asst_msg, rating, run_id))
     except Exception as e:
         print(f"[Feedback] 저장 실패: {e}")
 
@@ -184,7 +179,7 @@ def switch_user(user_id):
 
 def reset_chat(user_id):
     try:
-        asyncio.get_event_loop().run_until_complete(api_client.reset(user_id))
+        asyncio.run(api_client.reset(user_id))
     except Exception as e:
         print(f"[Reset] 실패: {e}")
     return [], []
@@ -199,7 +194,7 @@ def ingest_files(files):
     results = []
     for path in paths:
         try:
-            result = asyncio.get_event_loop().run_until_complete(api_client.ingest(path))
+            result = asyncio.run(api_client.ingest(path))
             name = os.path.basename(path)
             results.append(f"{name} → {result.get('chunks', '?')}개 청크")
         except Exception as e:
@@ -209,7 +204,7 @@ def ingest_files(files):
 
 def list_docs():
     try:
-        sources = asyncio.get_event_loop().run_until_complete(api_client.list_documents())
+        sources = asyncio.run(api_client.list_documents())
         return [[os.path.basename(s), s] for s in sources]
     except Exception as e:
         return [[f"오류: {e}", ""]]
@@ -219,7 +214,7 @@ def delete_doc(source):
     if not source.strip():
         return "삭제할 파일 경로를 입력하세요.", list_docs()
     try:
-        asyncio.get_event_loop().run_until_complete(api_client.delete_document(source.strip()))
+        asyncio.run(api_client.delete_document(source.strip()))
         return f"삭제 완료: {os.path.basename(source.strip())}", list_docs()
     except Exception as e:
         return f"오류: {e}", list_docs()