Fix transactions with compressed files

[Sanjays2402]

Compressed transactions currently queue the compression wrapper, so transaction exit calls commit() on GzipFile and raises AttributeError. Queue the raw filesystem file before applying compression; the wrapper still flushes on context exit, then the raw file commits normally.

The regression test reproduces the reported local gzip text write and verifies that the committed file decompresses to the original data.

Fixes #1584

[martindurant]

The windows failure looks genuine

[Sanjays2402]

You were right, it was genuine. The Windows job failed in test_transaction_with_compression with EOFError: Compressed file ended before the end-of-stream marker was reached.

Cause: GzipFile does not close the file object it wraps, so at transaction commit LocalFileOpener.commit() was calling shutil.move() on a temp file that still had buffered bytes and the pending gzip trailer. On posix the rename works on the open handle and the flush lands anyway, so the test passed; on Windows the move happens against a live handle and you get a truncated archive.

Fix is one hunk in LocalFileOpener.commit(): close self.f if it is still open before moving the temp file into place.

Verified locally on macOS (test_local.py + test_memory.py green, transaction tests green) — I do not have a Windows box, so I am relying on the pytest-win job here for confirmation.