ci: adopt shared Go lint workflow

[VinnyBarton]

Summary

• replace duplicated checkout, Go setup, dependency download, and golangci-lint steps with the shared Go lint workflow
• pin the shared workflow to merged commit 08214ced07c278eaed1c68fa459916e07f071553
• preserve the existing Go module location and golangci-lint v2.8 line

Security impact

The caller grants only contents read. External action maintenance moves into the reviewed shared workflow.

Validation

• Actionlint on the changed workflow: pass
• git diff --check: pass

Follow-up

Repository-wide Actions policy validation is intentionally deferred. It currently exposes existing ShellCheck findings in legacy build, SBOM, ReARM, and release workflows. Those findings should be removed through the next migration PRs rather than suppressed.

[VinnyBarton]

Superseded by #54. The lint-only split cannot meet the all-checks-pass requirement because the legacy OSV workflow fails while exporting oversized job outputs. PR #54 includes this lint migration, replaces that broken workflow, and has a fully green check suite.