Refactor: Remove background task management and related hooks

- Deleted `useBackgroundTasks.ts` hook and its associated logic for managing background tasks.
- Removed `backgroundTaskManager.ts` service and all related task definitions and registrations.
- Cleaned up `Podfile.lock` and `package.json` to remove unused dependencies related to background tasks.
- Updated iOS project files to eliminate references to removed background task components.
- Added new background fetch identifier in `Info.plist` for future use.

android/.gitignore

@@ -1,16 +0,0 @@
-# OSX
-#
-.DS_Store
-
-# Android/IntelliJ
-#
-build/
-.idea
-.gradle
-local.properties
-*.iml
-*.hprof
-.cxx/
-
-# Bundle artifacts
-*.jsbundle