M3 Review→Publish UI (#77): one-column flow, searchable pickers, fig/feat tags, e2e

- Review screen: slug-resolved species/wcat groupers, case-insensitive attrs,
  fig-*/feat-* tag pickers (METADATA-30/40), AI-assist labels + AI bubbles.
- App orchestrator: single writable flow store, capture→review→publish, Resume boot.
- API client (slabs.ts) mirroring live backend routes; Blob name fix.
- Playwright e2e (7 tests, hermetic mock): canvas PNG seed, client-UUID mock,
  SKU blur commit, ready-state reactive fix; expect timeout 4s, 2 workers.
- e2e green 7/7 in 6s; check_requirements + check_coverage PASS.

frontend/src/capture/session.ts

@@ -47,6 +47,8 @@ export interface CaptureSession {
   calculate(): Promise<void>;
   back(): void;
   getInventoryUrl(): string | null;
+  /** The current `measure` branch, or null while not on it (C2 handoff). */
+  currentMeasure(): Extract<Capture, { k: 'measure' }> | null;
   dispose(): void;
 }
 
@@ -632,6 +634,10 @@ export function createCaptureSession(opts: SessionOpts = {}): CaptureSession {
       return pngUrl;
     },
 
+    currentMeasure() {
+      return state.k === 'measure' ? state : null;
+    },
+
     dispose() {
       teardownWorker();
     },