Fixes TextEditingController used after being disposed the controller
was being manually disposed while the dialog's TextField still held a
reference during the pop animation. Now the dialog is its own
StatefulWidget so dispose() is called automatically by the framework
at the right time.
- AuthGate now tracks wasLoggedIn vs isLoggedIn and only calls setState
when the login status actually flips, preventing token-refresh events
from tearing down open dialogs and causing _dependents.isEmpty crashes
- Fix TextEditingController disposal order in scanner manual entry dialog
- Add camera, google_mlkit_text_recognition, image_picker, permission_handler deps
- Create ScannerScreen with live camera preview and OCR text recognition
- Auto-detect Hot Wheels IDs (e.g. JKF21) from captured photos using regex
- Add manual entry fallback dialog for typing HW ID by hand
- Update HomeScreen with scan FAB button and full DB query flow
- Query hotwheels table with .eq('hw_id', scannedCode).maybeSingle()
- Show 'Already in Collection' alert if car exists
- Show 'Add to Collection?' confirmation with insert if car is new
