refactor(web_api): fix import paths, modularize routers and decompose agent pipeline

modules/web_api/routers/chat.py

@@ -0,0 +1,60 @@
+"""
+===============================================================================
+FILE: modules/web_api/routers/chat.py
+ROLE: Маршрутизация диалогов с LLM (авторизованный и гостевой чаты).
+===============================================================================
+"""
+
+# ANCHOR[CHAT_ROUTER_IMPORTS]
+from typing import Optional, Dict, Any
+from fastapi import APIRouter, Depends, UploadFile, File, Form
+
+from .auth import get_current_user
+from llm.agent import process_chat_message
+from llm.file_parser import extract_text_from_file
+
+router = APIRouter(prefix="/api/v1/chat", tags=["chat"])
+
+# ANCHOR[CHAT_ENDPOINTS]
+@router.post("")
+async def chat_endpoint(
+    session_id: str = Form("web_session_main"),
+    message: str = Form(""),
+    file: Optional[UploadFile] = File(default=None),
+    current_user: Dict[str, Any] = Depends(get_current_user)
+):
+    """Диалог авторизованного пользователя с агентом."""
+    parsed_file = {"text": "", "image_b64": None}
+    if file and file.filename:
+        file_bytes = await file.read()
+        parsed_file = extract_text_from_file(file_bytes, file.filename)
+
+    reply, history, action_type = process_chat_message(
+        user_id=current_user["id"],
+        user_message=message,
+        file_context=parsed_file["text"],
+        image_b64=parsed_file["image_b64"],
+        session_id=session_id
+    )
+    return {"reply": reply, "history": history, "action_type": action_type}
+
+@router.post("/guest")
+async def guest_chat_endpoint(
+    session_id: str = Form("web_session_main"),
+    message: str = Form(""),
+    file: Optional[UploadFile] = File(default=None)
+):
+    """Гостевой диалог (user_id=0)."""
+    parsed_file = {"text": "", "image_b64": None}
+    if file and file.filename:
+        file_bytes = await file.read()
+        parsed_file = extract_text_from_file(file_bytes, file.filename)
+
+    reply, history, action_type = process_chat_message(
+        user_id=0,
+        user_message=message,
+        file_context=parsed_file["text"],
+        image_b64=parsed_file["image_b64"],
+        session_id=session_id
+    )
+    return {"reply": reply, "history": history, "action_type": action_type}