…amps61

Bootstrap of the full CI pipeline as it now sits at the tip of PR 820
(eduralph/addons-source@feature/ci-cd-pipeline-upstream, commit
3b2a947), landed directly on maintenance/gramps61 for an end-to-end
CI verification. This branch is a one-shot test bed: if Gary/Nick
merge the PR upstream, fork's maintenance/gramps61 will eventually be
forward-merged from gramps60, not from this state.

Equivalent shape to what the cherry-picked PR 820 contains:

  - .github/workflows/ci.yml — branch-neutral setup job (suffix /
    ci_image derived from github.ref_name); container jobs use
    needs.setup.outputs.ci_image; lint + unit-test-linux +
    unit-test-windows now blocking, addon-structure still advisory.
  - .github/workflows/docker-build.yml — branch-neutral params step
    (suffix, series, fallback SHA captured via git ls-remote of
    gramps-project/gramps@maintenance/gramps${suffix}); image tag
    derived; GRAMPS_FALLBACK_SHA threaded through as a build-arg so
    the buildx cache key invalidates when upstream tip moves.
  - .github/docker/gramps-ci/Dockerfile — required GRAMPS_SERIES arg;
    hybrid install (pip first, SHA-pinned git clone fallback when
    no gramps==${SERIES}.* exists on PyPI, fatal on any other pip
    failure).
  - .github/environment.yml — conda env for the Windows unit-test
    job (unchanged from PR 820's prior state).
  - tests/* — shared test harness (gramps_test_env.py base classes,
    test_plugin_registration.py).
  - .github/CI-MAINTAINER.md — runbook for the gramps-project
    maintainer covering one-time setup (GHCR visibility, first-push
    race), ongoing operations (new maintenance branches, PyPI
    release transitions), diagnostic log markers, and future-proofing
    knobs.

Expected on push:
  - docker-build fires; params step derives suffix=gramps61,
    series=6.1, fallback_sha=<current tip of gramps-project/gramps
    maintenance/gramps61>.
  - Dockerfile install logs ::warning::no gramps==6.1.* on PyPI;
    installing from gramps-project/gramps@maintenance/gramps61 at
    <sha>, since no 6.1.0 release exists yet.
  - Image published to ghcr.io/eduralph/addons-source/gramps-ci:
    gramps61.
  - First CI run: container jobs may race the image push (option 1
    first-push behavior documented in ci.yml header); re-run failed
    jobs once docker-build finishes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

…(2026-06-07)