fix: make repo-root path absolute

[2bndy5]

Keeping the repo-root path relative breaks parsing of absolute paths in clang-tidy output.

This didn't surface in the tests because they all use a compilation database generated for ninja (which uses relative paths). But in the test repo, we are using CMake which generates absolute paths in the compilation database.

Remember, clang-tidy outputs filenames however they are stated in the compilation database. If not using a compilation database, then clang-tidy just outputs the filename as it was given in the CLI.

I also removed an artifact debug log from developing the solution for #386

Summary by CodeRabbit

• Improvements
  • Enhanced error handling for repository root paths with improved error messages when invalid paths are provided.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI (base), Organization UI (inherited)

Review profile: CHILL

Plan: Pro

Run ID: 3db02df0-8cf5-4974-8e42-a816f2116b82

📥 Commits

Reviewing files that changed from the base of the PR and between 89f7b3d and caf7b2f.

📒 Files selected for processing (4)

• cpp-linter/src/clang_tools/clang_tidy.rs
• cpp-linter/src/common_fs.rs
• cpp-linter/src/git.rs
• cpp-linter/src/run.rs

💤 Files with no reviewable changes (1)

• cpp-linter/src/clang_tools/clang_tidy.rs

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📝 Walkthrough

Walkthrough

Introduces a mk_path_abs crate-level helper in common_fs.rs that canonicalizes a path and strips the Windows \\?\ extended-path prefix. Migrates git.rs and run.rs to use this helper, adds --repo-root canonicalization in run_main, removes a debug log from run_clang_tidy, and adds/updates related tests.

Changes

Path canonicalization refactor

Layer / File(s)	Summary
mk_path_abs helper and unit test cpp-linter/src/common_fs.rs	Adds pub(crate) fn mk_path_abs that calls canonicalize, strips a leading \\?\ from the result string, and returns a PathBuf. A new canonical_path test verifies the result is an existing file without the Windows extended-path prefix.
repo-root canonicalization in run_main cpp-linter/src/run.rs	Imports mk_path_abs, changes cli to mut, and inserts a canonicalization block that rewrites cli.source_options.repo_root to an absolute path and derives .gitmodules from it; returns an error with context when canonicalization fails.
git.rs migration, test updates, and debug log removal cpp-linter/src/git.rs, cpp-linter/src/run.rs, cpp-linter/src/clang_tools/clang_tidy.rs	Replaces manual fs::canonicalize + Windows-prefix trimming in clone_repo with mk_path_abs; removes the now-unused std::fs import. Drops a stale CLI argument from no_version_input and pre_commit_env tests. Adds bad_repo_root test asserting run_main errors on a non-existent --repo-root. Removes the parsed-notification-count debug log from run_clang_tidy.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• cpp-linter/cpp-linter-rs#347: Touches run.rs handling of --repo-root and the project cache directory, directly adjacent to the repo-root canonicalization added in this PR.
• cpp-linter/cpp-linter-rs#386: Adds the parsed-notifications debug log in run_clang_tidy that this PR removes.
• cpp-linter/cpp-linter-rs#358: Refactors run_clang_tidy and TidyAdvice caching in the same module where this PR removes the notification-count log.

🚥 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 'fix: make repo-root path absolute' clearly and concisely summarizes the main change—converting the repo-root path to an absolute path to fix parsing issues.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.59%. Comparing base (89f7b3d) to head (caf7b2f).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #387      +/-   ##
==========================================
+ Coverage   92.56%   92.59%   +0.03%     
==========================================
  Files          23       23              
  Lines        3710     3729      +19     
==========================================
+ Hits         3434     3453      +19     
  Misses        276      276              

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