feat: get clang-tidy fixes regardless of tidy-review value

[2bndy5]

This is another step toward presenting auto-fixed patches for consumers to commit/push.

This basically does what --tidy-review conditionally did before. But now it is done every time clang-tidy is invoked.

Even if not using the PR review feature, this allows us to boast if a clang-tidy note/warning can be auto-fixed. For example, the new thread comment may contain the following for something that can be auto-fixed:

• src/demo/demo.cpp:10:3 note: [readability]
  ⚡ auto-fix available

  {rationale}

  {concerned code snippet if any}

Summary by CodeRabbit

• New Features

  • Auto-fix availability indicator added to clang-tidy suggestions in review comments.

• Bug Fixes

  • More reliable caching and restoration of patched files to improve suggestion accuracy and stability.
  • Suggestion generation now consistently reads cached patched content.

• Tests

  • Tests updated to use isolated temporary workspaces and cover the new patch/restore behavior.

• Documentation

  • Spellcheck allowlist updated to include RAII.

[codecov]

Codecov Report

❌ Patch coverage is 84.31373% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.83%. Comparing base (793c310) to head (7079384).

Files with missing lines	Patch %	Lines
cpp-linter/src/clang_tools/clang_tidy.rs	76.81%	16 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #354      +/-   ##
==========================================
+ Coverage   92.74%   92.83%   +0.09%     
==========================================
  Files          22       23       +1     
  Lines        3403     3461      +58     
==========================================
+ Hits         3156     3213      +57     
- Misses        247      248       +1     

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 172982af-7170-4489-9502-69f156d653df

📥 Commits

Reviewing files that changed from the base of the PR and between d7902c3 and 7079384.

📒 Files selected for processing (4)

• cpp-linter/src/clang_tools/clang_tidy.rs
• cpp-linter/src/lib.rs
• cpp-linter/src/rest_client.rs
• cpp-linter/src/run.rs

Walkthrough

TidyAdvice.patched is now a PathBuf to a cached .tidy file. parse_tidy_output returns a Vec. run_clang_tidy always runs clang-tidy --fix-errors, caches patched files under CACHE_DIR, restores repo files via a RestoreOnDrop guard, and downstream code reads patched content from disk; UI shows auto-fix markers.

Changes

TidyAdvice File-Caching Refactor

Layer / File(s)	Summary
TidyAdvice contract and parse refactor cpp-linter/src/clang_tools/clang_tidy.rs	TidyAdvice.patched changes from Option<Vec<u8>> to PathBuf. Module imports updated. parse_tidy_output now returns Result<Vec<TidyNotification>, ClangCaptureError> and tests updated to inspect the returned Vec.
File caching and restoration in run_clang_tidy cpp-linter/src/clang_tools/clang_tidy.rs	Always adds --fix-errors, reads original file into RestoreOnDrop, runs clang-tidy to patch in-place, writes patched output to CACHE_DIR with .tidy extension, restores original repo file, disarms the guard, and sets file.tidy_advice with the cached path. Tests added/updated for stdout parsing and RestoreOnDrop behavior.
Patched content reading in make_suggestions_from_patch cpp-linter/src/common_fs.rs	Now loads patched content via fs::read_to_string(&advice.patched) (cached PathBuf) and passes it to make_patch for suggestions.
Auto-fix display and test data alignment cpp-linter/src/rest_client.rs	make_tidy_comment appends an auto-fix zap indicator when a note's line is in fixed_lines. Test data updated to set TidyNotification.patched to PathBuf::new() instead of None.
Test harness and temp workspace cpp-linter/src/run.rs	mod test made pub(crate) and adds setup_tmp_workspace() to copy demo assets into a temp dir; async tests updated to use per-test --repo-root pointing at the temp workspace.
Spell-check config cspell.config.yml	Add RAII to allowed words.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• cpp-linter/cpp-linter-rs#190: Modifies parse_tidy_output regex and note-header parsing logic, which this PR refactors further to change return types and responsibility boundaries.
• cpp-linter/cpp-linter-rs#347: Aligns with this PR's pattern of storing clang-format/clang-tidy patched output as PathBuf cached on disk rather than in-memory bytes.
• cpp-linter/cpp-linter-rs#77: Previously modified FileObj::make_suggestions_from_patch and diff-aware gating; closely related to how suggestions should be generated from cached patched content.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: obtaining clang-tidy fixes unconditionally, regardless of the tidy-review flag setting.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch tidy-fixes-always

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