feat(ci): add container build matrix check. Fixes #119

[prachimaskar]

Description of your changes

Implements the CI check proposed in #119.

• Added .github/scripts/check_container_build_matrix/ script that
  recursively discovers all Containerfile/Dockerfile paths under
  components/, pipelines/, and docs/examples/, and validates
  each has a matching context entry in container-build.yml
• Added .container-build-ignore file at repo root for excluding
  paths not intended to be built by CI (e.g. local-dev only)
• Added .github/workflows/container-build-matrix-check.yml workflow
  that triggers on PRs touching **/Containerfile, **/Dockerfile,
  or container-build.yml
• Added 18 unit tests following .github/scripts/ conventions

Checklist

• All tests and CI checks pass
• Pre-commit hooks pass without errors
• You have signed off your commits

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[Copilot]

Pull request overview

Adds a CI safeguard to ensure any Containerfile/Dockerfile introduced under the repo’s build roots is represented in the container-build.yml matrix, preventing CI from silently skipping new container builds.

Changes:

• Introduces a Python checker script to discover Containerfile/Dockerfile paths and validate they have matching context entries in .github/workflows/container-build.yml.
• Adds a repo-root .container-build-ignore mechanism to exclude intentionally unbuilt contexts.
• Adds a dedicated GitHub Actions workflow plus unit tests under .github/scripts/.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 7 comments.

File	Description
.github/workflows/container-build-matrix-check.yml	New workflow to run the matrix validation and script unit tests on relevant PR changes.
.github/scripts/check_container_build_matrix/check_container_build_matrix.py	Core discovery/parsing/checking logic + CLI and output formatting.
.github/scripts/check_container_build_matrix/tests/test_check_container_build_matrix.py	Unit/integration tests for discovery, parsing, ignore handling, and check results.
.container-build-ignore	New ignore file (initially documented, empty).

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[hbelmiro]

/ok-to-test

[prachimaskar]

Hi @HumairAK,
I've addressed the comments. Could you please review when you get a chance?
Thanks !😊