Re-enable clang-tidy checks for test and mock paths

[simon-d-bmw]

Background

PR #433 broadened the clang-tidy workflow exclusion pattern from 3rdparty to 3rdparty|/test/|/mock/ so that the CT-P1 production-code check enablement could be reviewed independently from test and mock findings.

That exclusion is intentionally temporary.

Goal

Re-enable the clang-tidy CI checks for test and mock paths once the production-code CT-P1 suppressions and fixes are merged and stable.

Acceptance criteria

• The --exclude pattern in .github/workflows/clang-tidy.yml no longer excludes /test/ and /mock/ paths.
• CI passes with the narrowed exclusion.
• Any remaining findings in test and mock code are either fixed, suppressed with a documented justification, or tracked in separate follow-up issues.