chore: initial project scaffold with Fastify server and Vite React app

Set up monorepo structure with server/ (Fastify + TypeScript) and web/ (React + Vite + TypeScript).
Includes package configs, dev proxy setup, and mobile-first CSS foundation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,11 @@
+{
+  "name": "spelljammer-ships",
+  "private": true,
+  "scripts": {
+    "dev": "concurrently -n server,web -c blue,green \"cd server && npm run dev\" \"cd web && npm run dev\"",
+    "install:all": "cd server && npm install && cd ../web && npm install"
+  },
+  "devDependencies": {
+    "concurrently": "^9.1.2"
+  }
+}