Add testing strategy: Vitest for unit tests, Playwright for E2E

- Vitest: unit tests for packages, components, and app logic (jsdom env,
  @testing-library/react, co-located test files)
- Playwright: E2E browser tests per app (journal.test.ts, planner.test.ts),
  auto-starts dev servers, scoped via testMatch
- Sample unit test for types package
- Smoke E2E tests for both apps
- Updated CLAUDE.md with test commands and strategy

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -11,19 +11,27 @@
     "dev": "turbo dev",
     "build": "turbo build",
     "lint": "turbo lint",
-    "test": "turbo test",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:e2e": "playwright test",
+    "test:e2e:ui": "playwright test --ui",
     "typecheck": "turbo typecheck"
   },
   "devDependencies": {
     "@eslint/js": "^10.0.1",
+    "@playwright/test": "^1.58.2",
     "@react-router/dev": "^7.13.1",
     "@react-router/node": "^7.13.1",
     "@react-router/serve": "^7.13.1",
     "@tailwindcss/vite": "^4.2.2",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "eslint": "^10.1.0",
     "eslint-config-prettier": "^10.1.8",
+    "jsdom": "^29.0.1",
+    "playwright": "^1.58.2",
     "prettier": "^3.8.1",
     "react": "^19.2.4",
     "react-dom": "^19.2.4",
@@ -31,6 +39,7 @@
     "tailwindcss": "^4.2.2",
     "turbo": "^2.8.20",
     "typescript-eslint": "^8.57.1",
-    "vite": "catalog:"
+    "vite": "catalog:",
+    "vitest": "^4.1.0"
   }
 }