internal: add fs_sync package

[Young-Flash]

No description provided.

[peter-jerry-ye-code-review]

‼️ This code review is generated by a bot. Please verify the content before trusting it.

⚠️ [Test leaves temporary files; potential cross-test contamination]

• Category: Correctness
• Code Snippet: blackbox_test.mbt test "write_and_read"
• Recommendation: Add cleanup steps after assertions:

  // After inspections
  @fs_sync.delete_file!(path_1)
  @fs_sync.delete_file!(path_2)

• Reasoning: The test creates files test_1.txt and test_2.txt but doesn't clean them up. This could cause false positives/negatives in subsequent test runs if files are not properly isolated.

⚠️ [Duplicate test execution steps in CI workflow]

• Category: Maintainability
• Code Snippet: .github/workflows/check.yml lines 266-276 vs 278-286
• Recommendation: Consolidate test steps using matrix conditions:

  - name: Run moon tests
    run: |
      {% raw %}moon test --target all
      moon test --release --target all
      moon test --target native{% endraw %}
    if: matrix.os != 'windows-latest'
  - name: Run Windows tests
    run: same-as-above
    if: matrix.os == 'windows-latest'

• Reasoning: Current implementation duplicates nearly identical test commands for Windows vs Unix-like systems, increasing maintenance burden.

⚠️ [Potential resource leak in native file handling]

• Category: Correctness
• Code Snippet: fs_sync_native.mbt read_file_to_bytes_internal (lines 59-69)
• Recommendation: Ensure file closure using defer pattern:

  let file = fopen_ffi(...)
  guard is_null(file) == 0 else { ... }
  defer fclose_ffi(file) // Add this
  
  // Rest of logic...

• Reasoning: If any guard condition fails after fopen_ffi, the file handle is never closed. This could lead to file descriptor leaks in long-running processes.

[coveralls]

Pull Request Test Coverage Report for Build 4884

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 16 of 20 (80.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.007%) to 82.951%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sync_io/sync_io_wasm.mbt	3	4	75.0%
sync_io/sync_io.mbt	2	5	40.0%

Totals
Change from base Build 4879:	0.007%
Covered Lines:	5065
Relevant Lines:	6106

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 4998

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 16 of 20 (80.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 84.827%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sync_io/sync_io_wasm.mbt	3	4	75.0%
sync_io/sync_io.mbt	2	5	40.0%

Totals
Change from base Build 4996:	0.0%
Covered Lines:	5233
Relevant Lines:	6169

---

💛 - Coveralls

[Young-Flash]

failed at stable & nightly as expected.

[Young-Flash]

var