Add output cleanup policy

app/config.py

@@ -2,6 +2,14 @@ import os
 from pathlib import Path
 
 
+def _get_bool_setting(name: str, default: bool) -> bool:
+    """Parse conventional boolean environment values."""
+    value = os.environ.get(name)
+    if value is None:
+        return default
+    return value.strip().lower() in {"1", "true", "yes", "on"}
+
+
 def _get_max_content_length() -> int:
     """Resolve the upload size limit from environment settings."""
     upload_limit_mb = os.environ.get("MAX_UPLOAD_SIZE_MB")
@@ -25,3 +33,6 @@ class Config:
     OUTPUT_DIRECTORY = Path(
         os.environ.get("OUTPUT_DIRECTORY", Path("instance") / "outputs")
     )
+    OUTPUT_RETENTION_HOURS = int(os.environ.get("OUTPUT_RETENTION_HOURS", 24))
+    CLEANUP_ON_STARTUP = _get_bool_setting("CLEANUP_ON_STARTUP", True)
+    CLEANUP_AFTER_DOWNLOAD = _get_bool_setting("CLEANUP_AFTER_DOWNLOAD", False)