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>

eslint.config.js

@@ -0,0 +1,10 @@
+import js from "@eslint/js";
+import tseslint from "typescript-eslint";
+import prettier from "eslint-config-prettier";
+
+export default tseslint.config(
+  { ignores: ["**/build/", "**/dist/", "**/.react-router/", "**/node_modules/"] },
+  js.configs.recommended,
+  ...tseslint.configs.recommended,
+  prettier,
+);