docs+store: oracle r3 follow-ups

- README test/smoke counts: 18→22, 26→28 (drifted across rounds)
- runLiveFetch keepCurrent now checks the MERGED catalog, not the old
  state — fixes the edge case where a scenarioId disappears between
  refreshes (would have orphaned the active scenario)

Constraint: no test changes; pure cleanup
Confidence: high
Scope-risk: narrow

README.md

@@ -95,14 +95,14 @@ pnpm fetch:scenarios
 pnpm dev                                # → http://127.0.0.1:5173
 
 # tests
-pnpm test                               # vitest, 18 tests across api, live,
-                                        # synthetic, layout
+pnpm test                               # vitest, 22 tests across api, live,
+                                        # synthetic, layout, store
 
 # build
 pnpm build                              # tsc + vite, single chunk ~225 KB gz
 
 # end-to-end smoke + screenshots
-pnpm qa:smoke                           # playwright headless, 26 assertions
+pnpm qa:smoke                           # playwright headless, 28 assertions
 
 # DOM layout audit
 pnpm qa:layout