fix: expand context window from 128h to 504h (21 days)

- Changed context_hours default from 128 to 504 hours
- This is the minimal change to fix invalid forecast patterns
- All other files unchanged from working commit 67808ce

src/forecasting/chronos_inference.py

@@ -114,7 +114,7 @@ class ChronosInferencePipeline:
         run_date: str,
         borders: Optional[List[str]] = None,
         forecast_days: int = 7,
-        context_hours: int = 128,
+        context_hours: int = 504,
         num_samples: int = 20
     ) -> Dict:
         """