migrated codebase to manifest v3

needed for chrome support

Author: kiing-dom

manifest.json

@@ -1,27 +1,23 @@
 {
-  "manifest_version": 2,
+  "manifest_version": 3,
   "name": "KeepCode",
-  "version": "0.4.1po",
+  "version": "0.4.1",
   "description": "Prep smarter for coding interviews! KeepCode tracks your LeetCode progress so you can focus on solving.",
   "permissions": ["storage", "tabs", "activeTab", "https://leetcode.com/*"],
   "background": {
-    "scripts": [
-      "background.js",
-      "browser-polyfill.js"
-    ],
-    "persistent": false
+    "service_worker": "background.js"  
   },
-  "browser_action": {
+  "action": {
     "default_popup": "popup/popup.html",
     "default_icon": "icons/keepcode-icon.png"
   },
   "content_scripts": [
     {
       "matches": ["https://leetcode.com/problems/*"],
       "js": [
+        "browser-polyfill.js",
         "leetcodeApi.js",
-         "content.js",
-         "browser-polyfill.js"
+         "content.js"
         ]
     }
   ],