Lock decision edge cases with business state tests

The dashboard risk is now mostly contradictory state combinations rather than styling. This extracts calendar action grouping into a pure utility and adds a lightweight TypeScript business-state runner so key decision states can be asserted without adding a test dependency.

Constraint: No new dependencies; use the existing TypeScript package for a local runner.

Rejected: Only rely on Next build/typecheck | it cannot catch product-language regressions such as fallback AI being labeled complete.

Confidence: high

Scope-risk: moderate

Reversibility: clean

Tested: npm run test:business

Tested: npm run build

Not-tested: Browser-rendered mobile fold interaction snapshots.

frontend/package.json

@@ -6,7 +6,8 @@
     "dev": "node scripts/sync-next-server-chunks.mjs --clean-root && next dev",
     "build": "next build && node scripts/sync-next-server-chunks.mjs",
     "start": "next start",
-    "lint": "next lint"
+    "lint": "next lint",
+    "test:business": "node scripts/run-business-state-tests.mjs"
   },
   "dependencies": {
     "@radix-ui/react-slot": "^1.1.2",