Add basic-server-vanillajs example

Demonstrates MCP App SDK usage with vanilla JavaScript (no framework),
providing parity with the existing basic-server-react example.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

examples/basic-server-vanillajs/tsconfig.json

@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "lib": ["ESNext", "DOM", "DOM.Iterable"],
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "verbatimModuleSyntax": true,
+    "noEmit": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true
+  },
+  "include": ["src", "server.ts"]
+}