ci: add coverage check workflow

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Summary

This PR improves the CI pipeline by adding a complete coverage reporting workflow and reorganizing PR checks.

Changes

• Add PR coverage workflow to generate and upload JaCoCo reports to Codecov
• Add base coverage upload workflow for develop and release_* branches
• Add a workflow to wait for Codecov project status to produce a stable PR check result
• Move multi-platform build checks into a separate workflow
• Add codecov.yml configuration for project coverage checks
• Upgrade some action version to use NodeJs 24

Coverage Check Sequence Diagram(s)

sequenceDiagram
    participant GH as GitHub (PR Event)
    participant CGB as Coverage Build<br/>(PR Gen Artifact)
    participant AS as Artifact Storage
    participant CUP as Codecov Upload<br/>(PR Upload)
    participant CV as Codecov API
    participant CPW as Coverage Project<br/>(Waiting)

    GH->>CGB: Trigger on PR to develop/<br/>release_*
    CGB->>CGB: Checkout, setup JDK 8,<br/>build project
    CGB->>CGB: Generate JaCoCo<br/>reports
    CGB->>AS: Upload jacoco-coverage<br/>artifact
    CGB-->>CUP: Workflow complete signal
    
    CUP->>AS: Download jacoco-coverage<br/>artifact
    CUP->>GH: Fetch PR details<br/>(PR number, SHA, branch)
    CUP->>CV: Upload coverage data<br/>with PR context
    CV-->>CUP: Coverage upload<br/>acknowledged

    CPW->>CV: Poll codecov/project<br/>status (every 30s)
    CV-->>CPW: Return status<br/>(pending/success/failure)
    CPW->>CPW: Check legacy commit<br/>statuses & check-runs
    
    alt Status Success
        CPW-->>GH: Job succeeds
    else Status Failure
        CPW-->>GH: Job fails
    else Still Pending
        CPW->>CPW: Wait 30s,<br/>retry (max 120x)
    end

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Notes

The coverage comparison report only take effect starting from the next PR.

[bladehan1]

Base coverage should be queried first, and regenerated only if coverage for a corresponding commit is not found. This improves efficiency.

[liuyifei001]

Let’s clarify the roles of the two secrets that only access in tronprotocol environment:

• secrets.CODECOV_TOKEN: used to upload coverage artifacts
• secrets.CODECOV_API_TOKEN: used to query coverage reports

Due to GitHub’s permission restrictions, secrets.CODECOV_API_TOKEN is not available in forked pull requests, which prevents querying the base repository’s coverage first.

In addition, the maintainers of java-tron have not configured secrets.CODECOV_API_TOKEN; only the upload token (secrets.CODECOV_TOKEN) is set.

[bladehan1]

It is recommended to merge the PR code coverage workflow files.

[liuyifei001]

Codecov Upload & Compare runs in tron-protocol environment triggered by another workflow, but Coverage Build can only runs in user' environment.

[bladehan1]

After uploading the coverage event, check whether it was successful.

[liuyifei001]

Workflow Codecov Upload & Compare replies on Coverage Build. If we merge Coverage Build and Waiting Coverage project, Codecov Upload & Compare can never be triggered.