Make secret file writes owner-only and working on Windows

[kwsantiago]

write_secret_file stores the duress recipients and freeze, the OPRF share and the LUKS key. On Windows it failed and was not owner-only:

• It fsyncs the parent directory after the rename by opening it as a file, which Windows refuses with Access is denied, so every write returned an error after the file was already in place. The Windows build on main has failed on this since the duress recipients tests landed.
• The owner-only 0600 mode is Unix-only, so on Windows the file took whatever access its directory passes down.

Changes:

• On Windows the temp file is created with an owner-only DACL marked protected, so nothing is inherited from the directory, using CREATE_NEW with FILE_FLAG_OPEN_REPARSE_POINT so an existing name or link is never reused or followed. The crash-dump writer shares this code and now also gets a protected DACL.
• On Windows the temp file replaces the target with MoveFileExW(MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH) in place of the rename and directory fsync; Unix is unchanged.
• CI runs the Windows tests on pull requests, without the release build that took most of that job's time (the release workflow builds the Windows binaries).

Tests: a new Windows test checks that a created file has exactly one ACE, a protected DACL, and refuses an existing name; it passes on the Windows runner in this PR's CI. The secret-file round-trip, payload and stale-temp tests now run on Windows too, and the three duress recipients tests that failed on Windows pass.

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Reviewing files that changed from the base of the PR and between 353abf4 and a955d2f.

📒 Files selected for processing (3)

• .github/workflows/ci.yml
• keep-cli/src/commands/frost_network/mod.rs
• keep-cli/src/panic_windows.rs

Walkthrough

After renaming a secret file, the code syncs its containing directory only on Unix. Unix directory-open or sync failures still return a runtime error.

Changes

Secret-file directory sync

Layer / File(s)	Summary
Unix directory sync keep-cli/src/commands/frost_network/mod.rs	The code opens and syncs the containing directory after rename only on Unix. Failures to open or sync it still return a runtime error.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: wksantiago

Merge Risk: 🟡 Moderate · up to 353ab

Windows enrollment can acknowledge a stored share without assurance that it will survive power loss. Establish a durable Windows write path before merging, or explicitly accept that risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title identifies Windows compatibility, which is a real objective of the change. The owner-only claim is not reflected in the provided change summary.

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_{A rabbit checks the rename is done,
Then syncs the directory under the sun.
On Unix, it waits for the write to stay,
Else skips that step and hops away.
The secret file rests safe in its place.}

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at @keep-cli/src/commands/frost_network/mod.rs:
- Line 1357: Update write_secret_file so Windows does not report success after a
rename without a persistence guarantee: use a replacement path that guarantees
durability, or return an error if none is available. Preserve the existing Unix
parent-directory sync behavior.

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• keep-cli/src/commands/frost_network/mod.rs

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