feat(systems): a System names its files — path patterns stored, validated and matched (milestone 444 step 3, #4756)

A System gains path_patterns: globs relative to the repo root (* within one
directory, ** across any depth, a plain directory covering everything under
it). One service validates them for every door, so the web UI and MCP refuse
the same bad pattern with the same message. systems_for_paths resolves paths
to every active System that covers them, which step 4 (#4757) uses to deliver
an area's rulings when its files are touched.

- schema: systems.path_patterns JSONB NOT NULL default [] (migration 0113)
- service: normalize_path_patterns, path_matches, systems_for_paths
- routes + MCP create_system/update_system accept it; [] clears
- web UI: a Files field in the create and edit forms, patterns on the card
- backup carries it through export and restore
- using-scribe reflex 7: tagging work keeps a System's files current

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_mcp_tool_systems.py

@@ -101,6 +101,23 @@ async def test_get_system_splits_records_by_kind():
     assert [r["id"] for r in result["notes"]] == [12]
 
 
+@pytest.mark.asyncio
+async def test_path_patterns_reach_the_service_from_both_tools():
+    """Omitted means unchanged; an empty list is a value — it clears them."""
+    with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \
+         patch("scribe.mcp.tools.systems.systems_svc") as svc:
+        svc.assess_system_name = AsyncMock(return_value=_NO_MATCH)
+        svc.create_system = AsyncMock(return_value=fake_system(name="Billing"))
+        svc.update_system = AsyncMock(return_value=fake_system(name="Billing"))
+        from scribe.mcp.tools.systems import create_system, update_system
+        await create_system(project_id=5, name="Billing", path_patterns=["src/billing"])
+        assert svc.create_system.await_args.kwargs["path_patterns"] == ["src/billing"]
+        await update_system(system_id=1, name="Billing")
+        assert "path_patterns" not in svc.update_system.await_args.kwargs
+        await update_system(system_id=1, path_patterns=[])
+        assert svc.update_system.await_args.kwargs["path_patterns"] == []
+
+
 @pytest.mark.asyncio
 async def test_update_system_not_found_raises():
     with patch("scribe.mcp.tools.systems.current_user_id", return_value=1), \