fix(extract): handle 0-result recheck gracefully — skip file write

When all proxy tiers are exhausted and 0 venues are fetched, the working
file is empty and compress_jsonl_atomic asserts non-empty. Return early
with a warning instead of crashing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py

@@ -522,6 +522,10 @@ def extract_recheck(
     dest_dir = landing_path(landing_dir, "playtomic", year, month)
     dest = dest_dir / f"availability_{target_date}_recheck_{recheck_hour:02d}.jsonl.gz"
 
+    if not venues_data:
+        logger.warning("Recheck fetched 0 venues (%d errors) — skipping file write", venues_errored)
+        return {"files_written": 0, "files_skipped": 0, "bytes_written": 0}
+
     captured_at = datetime.now(UTC).strftime("%Y-%m-%dT%H:%M:%SZ")
     working_path = dest.with_suffix("").with_suffix(".working.jsonl")
     with open(working_path, "w") as f: