Fixes #254

Root Cause
During each sync cycle, the worker was assigning System.currentTimeMillis() as the dateAdded value for every newly discovered track. Since all songs found in the same scan received the exact same timestamp, the Date Added sort in LibraryScreen couldn’t reflect the true order that MediaStore reported.

Fix
The worker now preserves MediaStore’s original DATE_ADDED value when inserting new tracks into the local database. It pulls this field directly from the cursor and converts it from seconds to milliseconds to align with the app’s expected format.

This ensures that each track keeps its correct timestamp from MediaStore, restoring accurate sorting by Date Added