windows: implement st_birthtime restoration, fixes #8730

[trxvorr]

This PR implements the restoration of file creation time (st_birthtime) on Windows, addressing Issue #8730.

Changes

• Platform Support: Added set_birthtime in src/borg/platform/init.py using ctypes and SetFileTime to precisely set creation time on NTFS.
• Archiver: Updated Archive.restore_attrs to call set_birthtime on Windows when birthtime metadata is present.
• Tests:
  • Added unit (win32_birthtime_test.py) and E2E (win32_birthtime_e2e_test.py) tests verifying birthtime preservation.
  • Updated is_birthtime_fully_supported and fixed test_nobirthtime to validly test birthtime behavior on Windows (handling st_birthtime != st_mtime semantics).

Verification

• Verified on Windows with Python 3.12+.
• New unit and E2E tests pass.
• Existing test_nobirthtime now passes locally on Windows.

[codecov]

Codecov Report

❌ Patch coverage is 52.00000% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.45%. Comparing base (2357071) to head (e3edd5b).
⚠️ Report is 650 commits behind head on master.

Files with missing lines	Patch %	Lines
src/borg/platform/base.py	55.55%	7 Missing and 1 partial ⚠️
src/borg/platform/__init__.py	20.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9341      +/-   ##
==========================================
- Coverage   76.50%   76.45%   -0.06%     
==========================================
  Files          85       85              
  Lines       14818    14823       +5     
  Branches     2214     2214              
==========================================
- Hits        11337    11333       -4     
- Misses       2803     2813      +10     
+ Partials      678      677       -1     

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[ThomasWaldmann]

Please update your local master branch and then rebase this branch onto that master and force push.

That should solve the CI test failures that are unrelated to your work.

[ThomasWaldmann]

some feedback

[ThomasWaldmann]

Check the CI, there are quite some failures.

[ThomasWaldmann]

@trxvorr Before I review, please:

• rebase on current master branch and fix the conflicts
• try to fix the CI failures

[ThomasWaldmann]

Same here, please rebase on current master, fix the conflicts, try to fix the CI failures.