add "lint-ext" job and fix manifest

package.json

@@ -5,6 +5,7 @@
   "license": "MIT",
   "scripts": {
     "build": "webpack --config webpack.config.js",
+    "lint-ext": "web-ext lint --source-dir=dist",
     "build-ext": "web-ext build --source-dir=dist --artifacts-dir=dist --overwrite-dest"
   },
   "devDependencies": {

public/manifest.json

@@ -11,7 +11,7 @@
   },
   "content_scripts": [
     {
-      "js": ["dist/main.js"],
+      "js": ["main.js"],
       "matches": ["*://*.lenameyerlandrut-fanclub.de/*"]
     }
   ],