chore: document v0.4 route and test status

docs/v0.4-route-status.md

@@ -0,0 +1,20 @@
+# v0.4 Route Status
+
+- `app/api/cases/start/route.js`
+  - Current tracked start-case route for the v0.4 graph orchestration path.
+  - Covered by `tests/app/api/cases-start-route.test.js`.
+
+- `app/api/start-case/route.js`
+  - Untracked earlier experiment / duplicate start route.
+  - Not referenced by the current UI.
+  - Still mentioned in untracked handoff docs.
+  - Leave untracked for now; recommend deletion once route migration is explicitly confirmed.
+
+- `app/api/update-case/route.js`
+  - Untracked future `updateCase` work.
+  - Not referenced by the current UI.
+  - Leave untracked for the current milestone.
+
+- Current UI status
+  - `components/scenario-form.jsx` still calls `/api/analyse`.
+  - No active UI path currently calls `/api/cases/start`, `/api/start-case`, or `/api/update-case`.