Address codex REQUEST_CHANGES + claude's live Forgejo measurements:
- ref_candidate_urls is host-only: same refs/tags then refs/heads on every
forge (Forgejo serves both paths; bare /archive/<ref> no longer special).
- bootstrap box raw fetch tries /raw/tag/ then /raw/branch/ and never
guesses kind from spelling; download is separate from execute.
- BOX_HOST defaults through RIG_HOST; comments narrow the zero-GitHub claim
(box@0.9.0 installer still hardcodes GitHub for its archive).
- SC2016 suppressions on the new grep assertions; tests updated.
install.sh resolves releases and archive URLs through RIG_HOST (default
GitHub), using Forgejo's single /archive/<ref>.tar.gz form and the same
/releases/latest redirect grammar. Bootstrap's box fetch gets BOX_HOST
with forge-aware raw-file URLs. Refusal hints and coolify Documentation=
stop pointing only at GitHub.
Closes#111
