feat(signal_v2-phase3b): main.py lifespan loads ChronosPredictor

AppContext.chronos field. lifespan: if KIS_APP_KEY set, load
ChronosPredictor(model_name=settings.chronos_model). Exceptions
during load logged + signal_v2 continues without chronos (other
endpoints unaffected). poll_loop receives chronos param.

45 tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

signal_v2/main.py

@@ -7,6 +7,7 @@ from contextlib import asynccontextmanager
 from fastapi import FastAPI
 
 from signal_v2 import state as state_mod
+from signal_v2.chronos_predictor import ChronosPredictor
 from signal_v2.config import get_settings
 from signal_v2.kis_client import KISClient
 from signal_v2.kis_websocket import KISWebSocket
@@ -24,6 +25,7 @@ class AppContext:
     poll_task: asyncio.Task | None = None
     kis_client: KISClient | None = None
     kis_ws: KISWebSocket | None = None
+    chronos: ChronosPredictor | None = None
 
 
 _ctx = AppContext()
@@ -69,10 +71,17 @@ async def lifespan(app: FastAPI):
         except Exception:
             logger.exception("KIS WebSocket startup failed — continuing without realtime asking_price")
 
+        # Load Chronos (heavy: ~1GB model download first time)
+        try:
+            _ctx.chronos = ChronosPredictor(model_name=settings.chronos_model)
+        except Exception:
+            logger.exception("ChronosPredictor load failed — continuing without chronos predictions")
+
     _ctx.poll_task = asyncio.create_task(
         poll_loop(
             _ctx.client, state_mod.state, _ctx.shutdown,
             kis_client=_ctx.kis_client,
+            chronos=_ctx.chronos,
         )
     )