feat: FF CSV bundled in image + auto-import on startup

- forex_factory_cache.csv moved to backend/ (Docker build context)
  → available at /app/forex_factory_cache.csv inside container
- main.py startup: auto-imports CSV in background thread if ff_calendar empty
  (idempotent — skips if rows already present)
- CSV path candidates: /app/ (Docker) → /tmp/ (upload) → local dev paths
- CalendarPage: remove Upload CSV + Import into DB buttons
  → replaced by auto-import status indicator + Sync Live only

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

backend/main.py

@@ -95,6 +95,33 @@ def startup():
     from services.institutional_scheduler import start_institutional_scheduler
     start_institutional_scheduler()
 
+    # Auto-import Forex Factory CSV if ff_calendar table is empty
+    import threading
+    def _auto_import_ff():
+        import time, os
+        from services.database import get_conn
+        from routers.eco import _find_csv, _run_ff_import, _ff_import_status
+        try:
+            conn = get_conn()
+            count = conn.execute("SELECT COUNT(*) FROM ff_calendar").fetchone()[0]
+            conn.close()
+            if count > 0:
+                print(f"[Startup] ff_calendar already has {count} rows — skipping auto-import", flush=True)
+                return
+            csv_path = _find_csv()
+            if not csv_path:
+                print("[Startup] forex_factory_cache.csv not found — skipping auto-import", flush=True)
+                return
+            print(f"[Startup] ff_calendar empty — auto-importing {csv_path} …", flush=True)
+            _run_ff_import(csv_path)
+            result = _ff_import_status.get("last_result") or {}
+            inserted = result.get("inserted", 0)
+            print(f"[Startup] FF auto-import done — {inserted} rows inserted", flush=True)
+        except Exception as e:
+            print(f"[Startup] FF auto-import error: {e}", flush=True)
+
+    threading.Thread(target=_auto_import_ff, daemon=True).start()
+
 
 @app.on_event("shutdown")
 def shutdown():