Convert the 6 build pack templates (standard, golang, helm, ruby, chef,
terraform) from hand-written YAML to Jsonnet. These are aggregation
components that compose individual components via include lists.

Critical for the mirror-aware implementation — build packs need to
cascade canonical_instance/mirror_instance inputs to child components.

AI-assisted: GitLab Duo Agentic Chat (Claude Opus 4.6)

chore(deps): update dependency gitlab-com/gl-infra/jsonnet-tool to v1.18.2

See merge request !1403

Convert build pack templates to Jsonnet

See merge request !1395

`command -v goimports` finds the mise shim even when mise can't resolve
it to an actual binary (no Go version set), causing a confusing error.
Add `mise which goimports` check to detect unresolvable shims.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

fix: check mise shim resolution in go-imports pre-commit hook

See merge request !1405

## [3.15.5](https://gitlab.com/gitlab-com/gl-infra/common-ci-tasks/-/compare/...) (2026-04-08)

### Fixes

* check mise shim resolution in go-imports pre-commit hook ([08e1f2ab](08e1f2ab))

### Others

* convert build pack templates to Jsonnet ([1ff7e112](1ff7e112))

### Dependencies

* **deps:** update dependency gitlab-com/gl-infra/jsonnet-tool to v1.18.2 ([05081b0a](05081b0a))