ci: check-coverage action pr commenting feature

[benceharomi]

Description

Added PR commenting functionality to the check-coverage GitHub action (post a comment with the result of the code coverage check to an opened PR).

Functional requirements

• The GitHub action is capable of adding a comment with the result of coverage check (percentage, percentage threshold, #lines covered)
• The GitHub action is capable of updating the previous comment it posted (to not spam the PR with comments after each change)

Testing requirements

Test passing coverage checks (these are tested in PR #3):

• coverage check passes -> action successful -> result commented
• success comment updated with fail comment
• success comment updated with success comment (with different %)

Test failing coverage checks (these are tested in PR #4):

• coverage check fails -> action unsuccessful -> result commented
• fail comment updated with success comment
• fail comment updated with fail comment (with different %)

[github-actions]

📊 Coverage Report

Metric	Coverage	Required	Status
Lines	100.00%	90%	✅ Above threshold

Details: 4 of 4 lines covered.

[Copilot]

Pull Request Overview

This PR improves the check-coverage GitHub action by adding functionality to post and update PR comments with the code coverage results. Key changes include:

• Adding branch filtering for push events and providing a github-token in the workflow.
• Updating the composite action to include robust file checks, validations, and PR comment update/creation logic.
• Enhancing logging and error messages for improved clarity in the coverage process.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.github/workflows/ci.yaml	Added branch filter for push events and passed the github-token to the action.
.github/actions/check-coverage/action.yaml	Extended the coverage check action with PR commenting capabilities and improved error handling.

Comments suppressed due to low confidence (1)

.github/actions/check-coverage/action.yaml:30

• [nitpick] Consider gating or consolidating debug log output with a verbosity flag to prevent excessive logging in production runs.

        echo "🔍 Debug: Processing coverage file \"${{ inputs.lcov_file }}\""

[zkfriendly]

Thanks. Looks good!