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>

tests/integration/test_boot.py

@@ -0,0 +1,42 @@
+"""Integration: boot the real app against a live Postgres.
+
+Creating the app with testing=False runs the core Alembic migrations AND every
+bundled plugin's migrations (discovered across all plugin roots). This is the
+canonical guard that the folded-in plugin migration graph resolves end-to-end —
+a pure-unit test can't catch a broken plugin revision chain.
+
+Requires STEWARD_DATABASE_URL pointing at a live Postgres; the integration CI
+lane provides it. Skipped automatically when unset so the unit lane stays green.
+"""
+from __future__ import annotations
+
+import asyncio
+import os
+
+import pytest
+
+pytestmark = pytest.mark.integration
+
+
+@pytest.mark.skipif(
+    not os.environ.get("STEWARD_DATABASE_URL"),
+    reason="integration test needs a live Postgres (STEWARD_DATABASE_URL)",
+)
+def test_real_boot_runs_all_migrations():
+    from sqlalchemy import text
+
+    from steward.app import create_app
+
+    # testing=False → init_db + run_core_migrations (core + all bundled-plugin
+    # migrations) + load_settings_sync + load_plugins all execute here.
+    app = create_app(testing=False)
+    assert app is not None
+
+    async def _roundtrip():
+        async with app.db_sessionmaker() as session:
+            # app_settings exists only if core migrations actually applied.
+            result = await session.execute(text("SELECT COUNT(*) FROM app_settings"))
+            return result.scalar()
+
+    count = asyncio.run(_roundtrip())
+    assert count is not None