Use Tangled Spindle for all CI and move build, publishing, and test helpers into ci/. Remove GitHub Actions and its environment-variable handling. Add branch: main to both PR triggers: without a branch pattern, Spindle recognizes the event type but never matches a PR.
Add a separate docs workflow that builds the Astro site into an Nginx image, checks the running container, and publishes cr.nym.sh/tasker-docs on main and release pushes. Main publishes edge; release tags publish both the exact tag and the version without v. Stable releases advance latest only when newer. PR and manual runs build and check without publishing; manual runs may omit TANGLED_REF.
Configure CR_USERNAME and CR_PASSWORD in Tangled's Pipelines → Secrets for docs publication. Server registry destinations and credentials remain as configured. Publishing runs must be serialized on the spindle/executor to avoid races on mutable tags; this limitation is documented.
Validation: all 29 CI helper tests pass; workflow YAML and PR target branches checked; server and docs images built and passed HTTP/container smoke checks. The docs image build also passed Astro diagnostics and checks for all 17 generated pages.