Add DB+.env auto backup with download and upload restore in Settings.

Backups land under /root/eth_hedge_backups; restore accepts zip body for new-server migration and restarts the process.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/api/__init__.py

@@ -1,6 +1,7 @@
 from fastapi import APIRouter
 
 from .auth_routes import router as auth_router
+from .backup_routes import router as backup_router
 from .market import router as market_router
 from .plan import router as plan_router
 from .settings import router as settings_router
@@ -16,3 +17,4 @@ router.include_router(plan_router)
 router.include_router(trades_router)
 router.include_router(stats_router)
 router.include_router(settings_router)
+router.include_router(backup_router)