fix(ci): support external and Dependabot PR service test workflows

[vishal-bala]

Summary

• update the manual external PR workflow to accept fork PRs and dependabot[bot] PRs while still requiring a maintainer-provided pr_number
• carry the PR number through job outputs and use it consistently in check-run messages
• add richer in-progress check details with a link to the active Actions run, plus the PR number and head SHA
• set persist-credentials: false when checking out external PR code and rename workflow/check labels from "Fork PR" to "External PR"
• skip service tests in the main test.yml workflow for Dependabot PRs

Testing

• Not run (not requested)

[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

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^{Security scan by Jit}