Fix core_entities_ci self path filter (.yml -> .yaml)

[MarkAlex1234]

Description of the changes

Commit 1 (the fix). .github/workflows/core_entities_ci.yaml lists .github/workflows/core_entities_ci.yml (with a .yml extension) under pull_request.paths. That file doesn't exist, so a PR that only edits this workflow doesn't run it. The change is never exercised before merge. This points the filter at the real file. One line.

Commit 2 (optional). This adds .github/workflows/path-filter-audit.yml, a small pull_request job that warns when a workflow's paths: list references a deleted or renamed workflow file, a directory without /**, or misses a local package a pipeline depends on (it reads uv/Poetry path sources). On main today it reports exactly this one finding; with commit 1, none. It only annotates and never fails the build; drop the commit if you'd rather not add a workflow.

Disclosure: the audit is a GitHub Action I maintain, dynamic-monorepo. It also runs in rajadilipkolli/spring-boot-microservices-series-v2.

Fixes / Resolves the following issues:

• None filed; small CI fix.

Checklist:

• Ensured the PR is named descriptively.
• Looked at the diff to make sure no unwanted files have been committed (1 line in commit 1, one new file in commit 2).
• Added label to PR: I can't set labels from a fork; bug would fit.