When `rust: true`, the rendered project gets:
  - the common-ci-tasks `rust` CI component (cargo-fmt,
    clippy, build, nextest+llvm-cov)
  - a `rust` toolchain pin in .tool-versions, exported as
    GL_ASDF_RUST_VERSION
  - /target/ in .gitignore
  - `builder: rust` + `command: zigbuild` in .goreleaser.yml
  - a unified `Dockerfile` (now distroless/cc-debian12 so the
    same image works for both Go static binaries and Rust's
    zigbuild glibc output)

The .goreleaser.yml.jinja and Dockerfile.jinja path conditions
widen from `{% if golang %}` to `{% if golang or rust %}` and
branch on the language internally. Both files remain in
`_skip_if_exists`, so existing rendered projects keep their
content untouched.

The temporary `goreleaser:` override at the bottom of
.gitlab-ci.yml.jinja points the release job at a dev-tagged
build from the in-flight images MR:
common-ci-tasks-images!1469
Remove that block once the MR merges and a new
common-ci-tasks-images release is tagged.

AI-assisted: Claude Code (claude-opus-4-7)

chore(deps): update dependency gitlab-com/gl-infra/platform/runway/fairway to v1.32.0

See merge request !760

chore(deps): update dependency gitlab-org/caproni to v2.55.0

See merge request !759

feat(rust): add language toggle with goreleaser

See merge request !737