feat(extract): add compress_jsonl_atomic() utility

Streams a JSONL working file to .jsonl.gz in 1MB chunks (constant memory),
atomic rename via .tmp sibling, deletes source on success. Companion to
write_gzip_atomic() for extractors that stream records incrementally.

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

extract/padelnomics_extract/src/padelnomics_extract/utils.py

@@ -174,3 +174,23 @@ def write_gzip_atomic(path: Path, data: bytes) -> int:
     tmp.write_bytes(compressed)
     tmp.rename(path)
     return len(compressed)
+
+
+def compress_jsonl_atomic(jsonl_path: Path, dest_path: Path) -> int:
+    """Compress a JSONL working file to .jsonl.gz atomically, then delete the source.
+
+    Streams compression in 1MB chunks (constant memory regardless of file size).
+    Atomic via .tmp rename — readers never see a partial .jsonl.gz.
+    Deletes the uncompressed working file after successful compression.
+    Returns compressed bytes written.
+    """
+    assert jsonl_path.exists(), f"source must exist: {jsonl_path}"
+    assert jsonl_path.stat().st_size > 0, f"source must not be empty: {jsonl_path}"
+    tmp = dest_path.with_suffix(dest_path.suffix + ".tmp")
+    with open(jsonl_path, "rb") as f_in, gzip.open(tmp, "wb") as f_out:
+        while chunk := f_in.read(1_048_576):  # 1 MB chunks
+            f_out.write(chunk)
+    bytes_written = tmp.stat().st_size
+    tmp.rename(dest_path)
+    jsonl_path.unlink()
+    return bytes_written