iOS push notification setup for client_app and mitra_app

- Add Runner.entitlements with aps-environment capability
- Add UIBackgroundModes (remote-notification, fetch) to Info.plist
- Add CODE_SIGN_ENTITLEMENTS to Debug/Release/Profile build configs
- Add GoogleService-Info.plist for both apps
- Upgrade Firebase packages and web_socket_channel to fix CocoaPods conflict
- Set client_app Podfile iOS platform to 15.0
- Fix mitra_app Xcode bundle ID to match Firebase (com.halobestie.mitra)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mitra_app/ios/Runner/Info.plist

@@ -24,6 +24,11 @@
 	<string>$(FLUTTER_BUILD_NUMBER)</string>
 	<key>LSRequiresIPhoneOS</key>
 	<true/>
+	<key>UIBackgroundModes</key>
+	<array>
+		<string>fetch</string>
+		<string>remote-notification</string>
+	</array>
 	<key>UILaunchStoryboardName</key>
 	<string>LaunchScreen</string>
 	<key>UIMainStoryboardFile</key>