scope frontend contracts to the feature, not to one file

93 test files read a single frontend source and asserted identifiers in it. The
MapWorkspace split showed what that costs: 24 tests went red for a move that
changed no behaviour at all. A contract belongs to the feature — a container,
its hooks, its domain layer — not to whichever file currently holds it.

232 read sites now resolve through read_feature(). The distinction that makes
this safe is direction: a *positive* contract ("this is wired") may widen,
because the identifier must still exist somewhere in the feature; a *negative*
one ("this component performs no transport") is a statement about one file, and
widening it would quietly weaken the check. The 73 single-file reads that
remain are exactly those, and a guard now enforces the rule for new tests.

Verified rather than assumed: of the 732 migrated positive assertions, 644 still
match exactly one module — as specific as before — and the other 86 already
spanned a container and its hook by nature. Two apparent misses are an artefact
of the checking regex reading an escaped newline literally.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/tests/test_sprint189_kempen_scope.py

@@ -5,6 +5,7 @@ from pathlib import Path
 import sys
 
 from shapely.geometry import Polygon, shape
+from tests.frontend_contract import read_feature
 
 
 ROOT = Path(__file__).resolve().parents[2]
@@ -127,7 +128,7 @@ def test_kempen_scope_operator_is_packaged_and_exposed_in_map_flow() -> None:
             (ROOT / "frontend/src/components/map/mapWorkspaceUtils.ts").read_text(encoding="utf-8"),
         )
     )
-    app = (ROOT / "frontend/src/App.tsx").read_text(encoding="utf-8")
+    app = read_feature("shell")
 
     assert "COPY scripts/geographic_scopes.py" in dockerfile
     assert "COPY scripts/provision_geographic_scope.py" in dockerfile
@@ -143,10 +144,10 @@ def test_kempen_scope_operator_is_packaged_and_exposed_in_map_flow() -> None:
 
 
 def test_project_switches_reset_scoped_state_and_prefer_the_regional_context() -> None:
-    bootstrap = (ROOT / "frontend/src/hooks/useWorkbenchBootstrap.ts").read_text(encoding="utf-8")
-    project_workspace = (ROOT / "frontend/src/hooks/useProjectWorkspace.ts").read_text(encoding="utf-8")
-    map_state = (ROOT / "frontend/src/hooks/useMapWorkspaceState.ts").read_text(encoding="utf-8")
-    dataset_workflow = (ROOT / "frontend/src/hooks/useDatasetWorkflow.ts").read_text(encoding="utf-8")
+    bootstrap = read_feature("shell")
+    project_workspace = read_feature("shell")
+    map_state = read_feature("map_workspace")
+    dataset_workflow = read_feature("datasets")
 
     selected_project_branch = bootstrap.split("if (!selectedProjectId)", maxsplit=1)[1]
     assert "resetProjectData()" in selected_project_branch