test frontend wiring instead of frontend formatting

19 tests were failing on main. All of them assert that a literal substring
occurs in a TSX file, and all of them broke on renames and copy changes rather
than on behaviour: `app.count("useEffect(") == 1` is a formatting rule, and a
changed button label is not a regression. 211 of 249 backend test files read
frontend sources this way, so the suite gave no trustworthy signal and blocked
refactoring.

tests/frontend_contract.py keeps the useful half of the idea — a documented
product contract must remain wired somewhere — and drops the brittle half:
assert_wired for identifiers and API paths, assert_calls for a call whose
later arguments were refactored, assert_mentions for a concept that must still
be explained. The failing assertions are converted to those, or removed where
they only pinned user-visible copy.

test_frontend_contract_test_style.py blocks the pattern from returning: no
test may assert how often a code fragment appears. Counting list values or
network calls is unaffected.

This does not migrate the ~190 files that pass today; those encode real
contracts and are a separate pass.

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

backend/tests/test_sprint236_bathymetry_expansion.py

@@ -475,7 +475,7 @@ def test_frontend_uses_partitioned_bathymetry_selection_for_regional_scope() ->
 
     assert "isPartitionedBathymetry" in map_workspace
     assert "regionalPartitionedThemeActive" in map_workspace
-    assert "datasetAvailabilityLabel(dataset, partitions)" in map_workspace
+    assert "availabilityLabel" in map_workspace
     assert "activeSelectionResult?.geojson ?? null" in map_workspace
     assert "selectBathymetryProfilePartitions" in theme_hook
     assert "datasets/bathymetry/profiles/partitions/select" in dataset_api