Add code to run npm start in both client & server

- Created a `run.js` script to automate the execution of `npm start` in both `client` and `server` directories.
- Added a check for `node_modules` to run `npm install` if missing before starting the applications.
- Updated root `package.json` with `install-all` and `start-all` scripts for easy installation and starting of both client and server simultaneously.

package.json

@@ -0,0 +1,17 @@
+{
+  "name": "appointment_to_examiner",
+  "version": "1.0.0",
+  "main": "run.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "install-all": "npm install --prefix client && npm install --prefix server",
+    "start-all": "node run.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "description": "",
+  "dependencies": {
+    "concurrently": "^9.1.2"
+  }
+}