Complete monorepo toolchain setup (tasks 1.1-1.7)

- Turborepo + pnpm workspaces with catalog for shared dependency versions
- TypeScript strict config (base + per-package extends)
- Tailwind CSS v4 via @tailwindcss/vite plugin
- ESLint + Prettier shared config
- Planner app scaffolded with React Router 7 (port 3001)
- Journal app scaffolded with React Router 7 (port 3000)
- Both apps build and start successfully via turbo

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

.prettierrc

@@ -0,0 +1,7 @@
+{
+  "semi": true,
+  "singleQuote": false,
+  "trailingComma": "all",
+  "printWidth": 100,
+  "tabWidth": 2
+}