ci: add Forgejo CI (lint + unit + Postgres integration) + ci-requirements.md

Single-repo CI now that plugins are bundled in-tree. Three lanes on push to
dev/main, modeled on FabledCurator's canonical ci.yml (minus frontend/Redis):
- lint: ruff check steward/ plugins/ tests/ (no dep install)
- unit: pytest -m 'not integration' — whole current suite (testing=True mocks DB)
- integration: postgres:16-alpine service via socket-discovered bridge IP; a
  boot-and-migrate test creates the real app, running core + all bundled-plugin
  migrations, then round-trips the DB — guards the folded-in migration graph.

Registers the 'integration' pytest marker; adds tests/integration/test_boot.py.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -37,6 +37,9 @@ steward = "steward.cli:main"
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
 testpaths = ["tests"]
+markers = [
+    "integration: requires a live Postgres; runs only in the integration CI lane",
+]
 
 [tool.hatch.build.targets.wheel]
 packages = ["steward"]