feat(coach): AI 코칭 버튼 및 버블 팝업 대화형 조언 기능 구현

apps/api/app/routes/sessions.py

@@ -130,6 +130,7 @@ class TurnRequest(BaseModel):
 
 class LiveCoachRequest(BaseModel):
     learner_text: str = Field(..., min_length=1)
+    question: Optional[str] = None
     client_reply: Optional[str] = None
     turn_seq: Optional[int] = Field(default=None, ge=1)
 
@@ -1673,6 +1674,7 @@ async def live_coach_turn(
         persona_code=sess.persona_code,
         persona_name=sess.persona.display_name,
         learner_text=body.learner_text,
+        question=body.question,
         client_reply=body.client_reply,
         recent_turns=sess.recent_turns(k=8, visible_to=LEARNER_VISIBLE_AI_ROLE),
         evaluation=_latest_turn_evaluation(sess, body.turn_seq),