Add Codecov coverage reporting to Maven workflow

[Copilot]

Integrates JaCoCo code coverage generation and Codecov reporting into the existing Maven CI workflow.

Changes

• pom.xml: Added JaCoCo Maven plugin (v0.8.12)

  • prepare-agent goal instruments test execution
  • report goal generates coverage XML during verify phase

• .github/workflows/maven.yml: Added Codecov upload step

  • Uses codecov/codecov-action@v5 with CODECOV_TOKEN secret
  • Set fail_ci_if_error: true for CI enforcement

• README.md: Added Codecov coverage badge

  • Badge displays current coverage percentage under the project title
  • Links to Codecov dashboard for detailed coverage reports

Coverage reports generate automatically on mvn clean verify package and upload to Codecov dashboard.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add Codecov report</issue_title>
<issue_description>Compute and report test coverage to Codecov via GitHub workflow. The existing maven workflow can be reused; just add steps as needed.

I already configured the Codecov secret key on GitHub.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add Codecov report #10

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[codecov]

Welcome to Codecov 🎉

Once you merge this PR into your default branch, you're all set! Codecov will compare coverage reports and display results in all future pull requests.

Thanks for integrating Codecov - We've got you covered ☂️

[Garciat]

@copilot let's add the Codecov coverage badge image thingy under the project title in the readme file.

[Copilot]

@copilot let's add the Codecov coverage badge image thingy under the project title in the readme file.

Added the Codecov badge to README.md in commit 96d7a14. The badge appears under the project title and will display the current coverage percentage while linking to the Codecov dashboard at https://codecov.io/gh/Garciat/java-type-classes.