Stabilize the decision workspace data boundaries

The scan terminal had grown into overlapping CSS, request-state, AI-provider, and city-card data responsibilities. This refactor separates those boundaries without changing product behavior: CSS modules are split by surface, city AI prompt/provider/fallback logic is isolated, and scan terminal request state now has reusable RemoteData adapters plus business-state tests.

Constraint: Preserve existing global scan-terminal class names and API responses during the refactor

Constraint: No new dependencies; keep this as a file-boundary cleanup

Rejected: Introduce React Query now | higher migration risk than the requested lightweight query-client path

Rejected: Rewrite AI stream behavior | progressive/fallback states are product-sensitive and were only adapter-split

Confidence: high

Scope-risk: moderate

Reversibility: clean

Directive: Keep AI stream state changes covered by business snapshots before changing fallback/cache wording

Tested: npm run test:business; npx tsc --noEmit; npm run build; python pytest -q; ruff check; py_compile targeted city AI modules

Not-tested: Live DeepSeek provider network replay and browser visual QA

.github/workflows/ci.yml

@@ -48,6 +48,9 @@ jobs:
       - name: Install dependencies
         run: npm ci
 
+      - name: Business state tests
+        run: npm run test:business
+
       - name: Build
         run: npm run build