Docs-only changes (docs/** or *.md) ran the full docker-build matrix (~9 min).
Each heavy job (test, migrations, functional-e2e, build) now runs
scripts/ci-detect-docs-only.sh as its first post-checkout step and gates every
real step on docs_only!='true'. The jobs still RUN and report success in
seconds, so the two required contexts keep reporting — a docs-only PR stays
mergeable (never an if:-skipped required job; Gitea 1.25.4 reports if-skip as
'skipped', verified with a throwaway probe PR). build skips its image steps on a
docs-only push to main; tag builds force docs_only=false. Detection uses
--no-renames so a code->docs rename can never be misclassified as docs-only.
Refs #416
timothy
5ba737bec7