Enable targeted clang-tidy readability checks

[scal444]

Enable a focused set of low-churn clang-tidy readability checks and apply their fixes to project sources.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge because the latest configuration expansion introduces no established build failure or behavioral regression.

Summary

This PR expands the project’s clang-tidy policy with focused readability checks, applies the corresponding mechanical fixes across C++ sources, and scopes analysis to project sources.

• Adds selected readability checks and a curated cppcoreguidelines configuration.
• Updates the clang-tidy runner’s source and header filters.
• Applies brace, container API, pointer qualification, and redundant-cast cleanups without changing intended runtime behavior.
• The previous checkout-path regex concern was manually resolved and is not outstanding.

_{Reviews (4) · Last reviewed commit: "Merge branch 'main' into codex/clang-rea..."}

[scal444]

The one I care about most here is the statement braces, since the models love to do one line indented statements that look awful. #308

[evasnow1992]

Changes look good to me. Just one comment regarding the removal of typename, which may cause a compilation error with Clang 15. Or we may want to update the readme file to recommend a different compiler/version?