Add Jin10 QR connection with cancellable login tasks

Store account credentials encrypted and bind QR tasks to administrator sessions. Report calendar access as awaiting validation after login.

Prevent late polls and status responses from overwriting cancelled or newer operations, and clean up QR tasks when settings unmount. Cover authentication, cancellation races, and stale frontend responses.

backend/src/alphapulse/api/main.py

@@ -5,7 +5,7 @@ from fastapi.exceptions import RequestValidationError
 from fastapi.responses import RedirectResponse
 from starlette.exceptions import HTTPException
 
-from alphapulse.api import auth, calendar, chat, crawler, market, news, settings, skills, trading, risk
+from alphapulse.api import auth, calendar, chat, crawler, market, news, settings, skills, trading, risk, jin10
 from alphapulse.api.response import (
     ApiResponse, ValidationErrors, http_error, internal_error, success, validation_error,
 )
@@ -30,6 +30,7 @@ app.include_router(chat.router)
 app.include_router(trading.router)
 app.include_router(calendar.router)
 app.include_router(risk.router)
+app.include_router(jin10.router)
 
 
 @app.get("/api/health", include_in_schema=False)