feat(attestation): Include attestation output automatically on GitHub and GitLab reports

[javirln]

This PR adds automatic attestation report generation for GitHub Actions and GitLab CI platforms.

Changes

Runner Interface Extension

Extended the SupportedRunner interface with a Report(tableOutput []byte) error method. This method is called by the CLI command layer after successful attestation push to write formatted attestation status to platform-specific locations.

Platform Implementations

• GitHub Actions: Writes attestation table to $GITHUB_STEP_SUMMARY wrapped in a markdown code block, making it visible in the job summary UI
• GitLab CI: Writes attestation table to chainloop-attestation-report.txt as a downloadable artifact with instructions on how to access it
• Other runners: No-op implementation (returns nil)

CLI Integration

The attestation push command now automatically reports attestation status to the CI/CD platform after successful push. The runner instance is accessed via AttestationResultRunnerContext.RawRunner and the report is rendered using existing table formatting functions from the cmd layer.

Opt-out Support

Added --deactivate-ci-report flag to disable automatic reporting when needed.

Error Handling

Report failures are logged as warnings but do not fail the attestation push operation.

Examples

GitHub

GitLab

Ref: #2667

[javirln]

Not adding a color by default was causing the output to look likes this:

│ Timestamp Authority       │ http://timestamp.digicert.com                                           │
│ Policy violation strategy │ �[0mADVISORY�[0m                                                                │
└───────────────────────────┴─────────────────────────────────────────────────────────────────────────┘
┌───────────────────────────────────────────────────────────────────────────────┐
│ Runner context                                                                │
├─────────────────────────┬─────────────────────────────────────────────────────┤