Fix census download crash at 100K: integer out of range

safe_int now clamps values to PostgreSQL INTEGER max (2.1B) and
handles scientific notation. Mileage columns changed to BIGINT
on prod since carriers can have >2B annual miles.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/workers/fmcsa_census_downloader.py

@@ -59,13 +59,16 @@ def parse_fmcsa_date(date_str: str | None) -> str | None:
     return None
 
 
-def safe_int(val) -> int | None:
-    """Convert value to int, handling strings and None."""
+def safe_int(val, max_val: int = 2_147_483_647) -> int | None:
+    """Convert value to int, handling strings, None, and out-of-range values."""
     if val is None:
         return None
     try:
-        return int(val)
-    except (ValueError, TypeError):
+        v = int(float(val))  # handle "1.234e7" scientific notation
+        if v > max_val or v < -max_val:
+            return None  # out of range for PostgreSQL INTEGER
+        return v
+    except (ValueError, TypeError, OverflowError):
         return None