Scaffold monorepo: engine, server, and web packages

npm workspaces with three TypeScript packages: @wizwar/engine (pure
game logic), @wizwar/server (Node websocket authority), @wizwar/web
(Svelte 5 + Vite client). Server handshake and client build verified.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

package.json

@@ -0,0 +1,18 @@
+{
+  "name": "wizwar",
+  "private": true,
+  "version": "0.1.0",
+  "description": "Web-based Wiz-War (6th edition rules)",
+  "workspaces": [
+    "packages/*"
+  ],
+  "scripts": {
+    "dev": "npm run dev --workspace=@wizwar/server & npm run dev --workspace=@wizwar/web",
+    "build": "npm run build --workspaces",
+    "test": "npm run test --workspaces --if-present",
+    "typecheck": "npm run typecheck --workspaces"
+  },
+  "engines": {
+    "node": ">=20"
+  }
+}