ChaloTrain Android App Full Production

I need complete end-to-end production work for my ChaloTrain Android app. I already have the Kotlin + Jetpack Compose project with UI, navigation and basic local functionality. You need to take the existing project and make it fully production-ready. Complete responsibility includes: Audit and fix the existing Android project/build configuration. Complete all railway API integrations: Search Train PNR Status Live Train Status Train Schedule Trains Between Stations Seat Availability Fare Enquiry Live Station Train Classes Train/Station Search Build/use a secure backend/API proxy. API keys must never be exposed inside the APK. Proper API response mapping, validation, caching, timeout, rate-limit handling and error handling. Remove all remaining mock, fake, demo or development-only railway data. Connect every screen properly to the real backend/API. Test all features with real API responses. Fix crashes, navigation issues, loading/empty/error/offline states and production bugs. Verify Light/Dark mode, languages, persistence and all existing app functionality. Test on real Android devices and different screen sizes. Optimize performance and production configuration. Configure release signing and generate a signed AAB. Verify the release build and install/test it before submission. Prepare Play Store listing assets and required technical declarations. Configure Play Console testing/release requirements. Upload and submit the app to Google Play Console. Handle technical build/submission issues and fix app-related Play Store rejection issues within the agreed scope. Deliver the complete Android source code, backend source code, configuration/documentation and release AAB. Important: Do not rebuild the project unnecessarily and do not replace the existing UI unless a production issue requires it. No fake railway data and no API keys/secrets in the Android app. Please inspect the project first and give me: (1) fixed total price, (2) delivery timeline, (3) exact milestones, and (4) confirmation that you will handle the work from the current project through Play Store submission. Google Play approval itself is subject to Google’s review, but all app/build/submission issues within your technical scope must be handled.