fix: keep paper trading active without approved model

crypto_spot_bot/config.py

@@ -171,6 +171,7 @@ class Settings:
     storage_prune_interval_seconds: int = 3600
     bybit_rest_base_url_override: str = ""
     bybit_websocket_url_override: str = ""
+    time_series_fallback_mode: str = "trend_macd"
 
     @property
     def rest_base_url(self) -> str:
@@ -354,6 +355,9 @@ def load_settings(env_file: str | Path | None = None) -> Settings:
             "" if _bool_env("BYBIT_TESTNET", False) else "https://api.bybit.kz",
         ).strip(),
         bybit_websocket_url_override=os.getenv("BYBIT_WEBSOCKET_URL", "").strip(),
+        time_series_fallback_mode=os.getenv(
+            "TIME_SERIES_FALLBACK_MODE", "trend_macd"
+        ).strip().lower(),
     )
     _validate_settings(settings)
     if settings.trading_mode == "live" and not settings.live_ready:
@@ -390,6 +394,8 @@ def _validate_settings(settings: Settings) -> None:
         errors.append("LIVE_ORDER_FILL_TIMEOUT_SECONDS must be positive")
     if settings.live_reconciliation_interval_seconds <= 0:
         errors.append("LIVE_RECONCILIATION_INTERVAL_SECONDS must be positive")
+    if settings.time_series_fallback_mode not in {"trend_macd", "legacy"}:
+        errors.append("TIME_SERIES_FALLBACK_MODE must be trend_macd or legacy")
     if errors:
         raise ValueError("; ".join(errors))