feat: Integrate dotenv for environment variable management and update .gitignore

pubspec.yaml

@@ -50,6 +50,7 @@ dependencies:
   geolocator: ^14.0.2
   google_places_flutter: ^2.1.1
   http: ^1.5.0
+  flutter_dotenv: ^6.0.0
 
 dev_dependencies:
   flutter_test:
@@ -76,6 +77,7 @@ flutter:
   # To add assets to your application, add an assets section, like this:
   assets:
      - assets/icons/
+     - .env
      #- assets/images/
 
   # An image asset can refer to one or more resolution-specific "variants", see