feat: VaR/PnL schedulers + snapshots DB + page sur bouton

Backend:
- Tables var_snapshots + pnl_snapshots dans SQLite (contexte macro + prix tickers)
- var_service.py : save_var_snapshot, save_pnl_snapshot + fonctions get_*
- var_scheduler.py : threads APScheduler pour VaR (défaut 6h) et PnL (défaut 1h)
- router var.py : /run-now (POST compute+save), /latest, /snapshots, /pnl/run-now,
  /pnl/latest, /scheduler/status, /scheduler/config
- main.py : démarrage des deux schedulers au startup

Frontend:
- VaRAnalysis.tsx : plus d'auto-fetch ; charge le dernier snapshot DB au mount ;
  bouton "Calculer" → POST /run-now ; erreur backend = message clair ; historique
  de snapshots sélectionnables
- Config.tsx : section "Schedulers VaR & PnL" dans l'onglet cycle avec toggle
  enable/disable, intervalle, et boutons "Snapshot maintenant"

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

backend/routers/var.py

@@ -1,20 +1,107 @@
-from fastapi import APIRouter, Query
-from services.var_service import compute_var
+from fastapi import APIRouter, Query, HTTPException
+from pydantic import BaseModel
+from services.var_service import (
+    compute_var, save_var_snapshot,
+    get_var_snapshots, get_var_snapshot, get_latest_var_snapshot,
+    get_pnl_snapshots, get_latest_pnl_snapshot, save_pnl_snapshot,
+)
+from services.var_scheduler import (
+    get_scheduler_status, restart_var_scheduler, restart_pnl_scheduler,
+)
+from services.database import set_config
 
 router = APIRouter(prefix="/api/var", tags=["var"])
 
 
-@router.get("/compute")
-def var_compute(
+@router.get("/latest")
+def var_latest():
+    """Get most recent saved VaR snapshot (no recompute)."""
+    snap = get_latest_var_snapshot()
+    return {"snapshot": snap}
+
+
+@router.get("/snapshots")
+def var_snapshots(limit: int = Query(default=20, ge=1, le=100)):
+    """List recent VaR snapshot summaries."""
+    return {"snapshots": get_var_snapshots(limit)}
+
+
+@router.get("/snapshots/{snapshot_id}")
+def var_snapshot_detail(snapshot_id: int):
+    snap = get_var_snapshot(snapshot_id)
+    if not snap:
+        raise HTTPException(404, "Snapshot not found")
+    return snap
+
+
+@router.post("/run-now")
+def var_run_now(
     confidence: float = Query(default=0.95, ge=0.90, le=0.99),
     horizon_days: int = Query(default=1, ge=1, le=30),
     lookback_days: int = Query(default=252, ge=60, le=504),
     default_iv: float = Query(default=0.20, ge=0.05, le=0.80),
 ):
-    """Compute portfolio VaR using Black-Scholes delta approach."""
-    return compute_var(
+    """Compute VaR now and save to DB. Returns the full result."""
+    result = compute_var(
         confidence=confidence,
         horizon_days=horizon_days,
         lookback_days=lookback_days,
         default_iv=default_iv,
     )
+    if "error" in result:
+        raise HTTPException(400, result["error"])
+    snapshot_id = save_var_snapshot(
+        result, confidence, horizon_days, lookback_days, default_iv
+    )
+    return {**result, "snapshot_id": snapshot_id}
+
+
+# ─── PnL endpoints ───────────────────────────────────────────────────────────
+
+@router.get("/pnl/latest")
+def pnl_latest():
+    return {"snapshot": get_latest_pnl_snapshot()}
+
+
+@router.get("/pnl/snapshots")
+def pnl_snapshots(limit: int = Query(default=48, ge=1, le=200)):
+    return {"snapshots": get_pnl_snapshots(limit)}
+
+
+@router.post("/pnl/run-now")
+def pnl_run_now():
+    try:
+        row_id = save_pnl_snapshot()
+    except Exception as e:
+        raise HTTPException(500, str(e))
+    return {"snapshot_id": row_id, "snapshot": get_latest_pnl_snapshot()}
+
+
+# ─── Scheduler status / config ───────────────────────────────────────────────
+
+@router.get("/scheduler/status")
+def scheduler_status():
+    return get_scheduler_status()
+
+
+class SchedulerConfig(BaseModel):
+    var_enabled: bool | None = None
+    var_hours: float | None = None
+    pnl_enabled: bool | None = None
+    pnl_hours: float | None = None
+
+
+@router.post("/scheduler/config")
+def scheduler_config(cfg: SchedulerConfig):
+    if cfg.var_enabled is not None:
+        set_config("var_scheduler_enabled", "true" if cfg.var_enabled else "false")
+    if cfg.var_hours is not None:
+        set_config("var_scheduler_hours", str(cfg.var_hours))
+    if cfg.pnl_enabled is not None:
+        set_config("pnl_scheduler_enabled", "true" if cfg.pnl_enabled else "false")
+    if cfg.pnl_hours is not None:
+        set_config("pnl_scheduler_hours", str(cfg.pnl_hours))
+    # Restart scheduler threads to pick up new config
+    restart_var_scheduler()
+    restart_pnl_scheduler()
+    return {"ok": True, "status": get_scheduler_status()}