chore: add consistent start targets and Makefiles across examples

Author: mridang

Makefile

@@ -0,0 +1,5 @@
+.PHONY: start
+
+start:
+	npm install
+	npm start

README.md

@@ -99,7 +99,9 @@ cd example-auth-solidstart
 npm install
 
 # 3. Start the development server
-npm run dev
+npm start
+# or
+make start
 ```
 
 The application will now be running at `http://localhost:3000`.

package.json

@@ -13,9 +13,9 @@
     "seroval": "1.4.2"
   },
   "scripts": {
+    "start": "vinxi dev",
     "dev": "vinxi dev",
     "build": "vinxi build",
-    "start": "vinxi start",
     "preview": "vite preview",
     "format": "prettier --write .",
     "lint": "prettier --check . && eslint .",