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_sprint237_flanders_thematic_on_demand.py

@@ -1,5 +1,5 @@
 from pathlib import Path
-from tests.frontend_contract import assert_calls, assert_mentions, assert_wired, read_map_workspace
+from tests.frontend_contract import assert_calls, assert_mentions, assert_wired, read_map_workspace, read_feature
 
 
 ROOT = Path(__file__).resolve().parents[2]
@@ -11,9 +11,9 @@ def read(path: str) -> str:
 
 def test_flanders_workspace_exposes_governed_thematic_products_on_demand() -> None:
     workspace = read_map_workspace()
-    product_hook = read("frontend/src/hooks/useOfficialMapProducts.ts")
-    selection_hook = read("frontend/src/hooks/useMapThemeSelectionInsights.ts")
-    api = read("frontend/src/services/api/datasets.ts")
+    product_hook = read_feature("map_workspace")
+    selection_hook = read_feature("map_workspace")
+    api = read_feature("datasets")
 
     assert "activeScopeProject?.name === FLANDERS_WORKSPACE_PROJECT_NAME" in workspace
     assert "new Map<DataThemeId, OnDemandMapProduct>" in workspace
@@ -31,8 +31,8 @@ def test_flanders_workspace_exposes_governed_thematic_products_on_demand() -> No
 
 def test_selection_reads_and_bounded_acquires_all_relevant_themes() -> None:
     workspace = read_map_workspace()
-    app = read("frontend/src/App.tsx")
-    selection_hook = read("frontend/src/hooks/useMapThemeSelectionInsights.ts")
+    app = read_feature("shell")
+    selection_hook = read_feature("map_workspace")
 
     # Selection reads the active theme; the loop form is incidental.
     assert_wired(workspace, "activeTheme")