extract the map workspace's domain layer out of the component

MapWorkspace.tsx opened with ~590 lines of theme catalogue, dataset matching
and label formatting above a 3.200-line component. None of it is React, all of
it is independently testable, and both render paths read from it, so it belongs
beside the pure helpers that already live in mapWorkspaceUtils.

The contract tests that read MapWorkspace.tsx would have gone red for a move
that changes no behaviour at all — 24 of them. That is the brittleness the
frontend_contract helper exists to remove, so it gains read_map_workspace():
the workspace is one feature spread over several modules, and a contract
belongs to the feature rather than to whichever file currently holds it.

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

backend/tests/test_sprint233_operational_completion.py

@@ -20,7 +20,7 @@ from app.services.storage_service import StorageService
 from app.services.source_registry_service import SourceRegistryService
 from app.services.temporal_analysis_service import TemporalAnalysisService
 from app.services.thematic_raster_analysis_service import ThematicRasterAnalysisService
-from tests.frontend_contract import assert_calls, assert_mentions, assert_wired
+from tests.frontend_contract import assert_calls, assert_mentions, assert_wired, read_map_workspace
 
 
 class FakeSession:
@@ -364,7 +364,7 @@ def test_map_result_export_endpoint_uses_canonical_envelope(monkeypatch) -> None
 
 def test_frontend_persists_map_result_before_opening_downloads() -> None:
     root = Path(__file__).resolve().parents[2]
-    workspace = (root / "frontend/src/components/map/MapWorkspace.tsx").read_text(encoding="utf-8")
+    workspace = read_map_workspace()
     hook = (root / "frontend/src/hooks/useExportWorkflow.ts").read_text(encoding="utf-8")
     api = (root / "frontend/src/services/api/exports.ts").read_text(encoding="utf-8")