fix(web): restructure client as standalone Vite project

- client/ now has its own package.json (independent Vite project)
- Tailwind + PostCSS config inlined into vite.config.ts
- dev:client uses `cd client && npm run dev` (CWD = Vite root)
- Root package.json only has server deps
- Fix tsconfig deprecation (remove baseUrl)
- Add `npm run setup` for one-command install

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/client/tsconfig.json

@@ -4,7 +4,6 @@
     "jsx": "react-jsx",
     "outDir": "./dist",
     "rootDir": "./src",
-    "baseUrl": ".",
     "paths": {
       "@/*": ["./src/*"]
     }