feat: make MCP SDK a peer dependency

- Move @modelcontextprotocol/sdk from dependencies to peerDependencies (^1.20.0)
- Add to devDependencies for local development (^1.24.3)
- Externalize SDK from all build entry points (app, app-bridge, react, server)

Benefits:
- Consumers control their SDK version
- Deduplication when consumer already has SDK
- Follows pattern of react/zod peer deps

Author: ochafik

build.bun.ts

@@ -23,13 +23,20 @@ function buildJs(entrypoint: string, opts: Record<string, any> = {}) {
 }
 
 await Promise.all([
-  buildJs("src/app.ts", { outdir: "dist/src" }),
+  buildJs("src/app.ts", {
+    outdir: "dist/src",
+    external: ["@modelcontextprotocol/sdk"],
+  }),
   buildJs("src/app-bridge.ts", {
     outdir: "dist/src",
     external: ["@modelcontextprotocol/sdk"],
   }),
   buildJs("src/react/index.tsx", {
     outdir: "dist/src/react",
-    external: ["react", "react-dom"],
+    external: ["react", "react-dom", "@modelcontextprotocol/sdk"],
+  }),
+  buildJs("src/server/index.ts", {
+    outdir: "dist/src/server",
+    external: ["@modelcontextprotocol/sdk"],
   }),
 ]);

package.json

@@ -59,6 +59,7 @@
   },
   "author": "Olivier Chafik",
   "devDependencies": {
+    "@modelcontextprotocol/sdk": "^1.24.3",
     "@playwright/test": "^1.52.0",
     "@types/bun": "^1.3.2",
     "@types/react": "^19.2.2",
@@ -79,6 +80,7 @@
     "zod": "^4.1.13"
   },
   "peerDependencies": {
+    "@modelcontextprotocol/sdk": "^1.20.0",
     "react": "^17.0.0 || ^18.0.0 || ^19.0.0",
     "react-dom": "^17.0.0 || ^18.0.0 || ^19.0.0",
     "zod": "^3.25.0 || ^4.0.0"
@@ -92,7 +94,6 @@
     }
   },
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.24.3",
     "prettier": "^3.6.2"
   },
   "optionalDependencies": {