chore: update Fastlane configuration and clean up API service

- Updated the Deliverfile to submit for review and skip metadata and screenshots.
- Removed outdated build lane from Fastfile.
- Refactored API service to eliminate fallback to latest assistant message, addressing duplication issues in multi-turn conversations.

ios/fastlane/Deliverfile

@@ -1,3 +1,7 @@
 # The Deliverfile allows you to store various App Store Connect metadata
 # For more information, check out the docs
 # https://docs.fastlane.tools/actions/deliver/
+submit_for_review(true)
+skip_metadata(true)
+skip_screenshots(true)
+ipa("../build/ios/ipa/conduit.ipa")

ios/fastlane/Fastfile

@@ -11,15 +11,4 @@
 #
 
 # Uncomment the line if you want fastlane to automatically update itself
-# update_fastlane
-
-default_platform(:ios)
-
-platform :ios do
-  desc "Push a new release build to the App Store"
-  lane :release do
-    skip_build_archive: true,
-    archive_path: "../build/ios/archive/Runner.xcarchive",
-    upload_to_app_store
-  end
-end
+# update_fastlane