Offline queue (SharedPreferences) persists captures when the device
is offline and replays them as chat conversations on next launch,
preserving the same fire-and-forget guarantee as the online path.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Replace POST /api/quick-capture with: create a conversation, send the
message, and fire-and-forget the SSE generation stream so the assistant
processes the request in the background without blocking the UI.
The new conversation appears immediately in the chat tab.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Migrate StateNotifierProvider/StateNotifier → NotifierProvider/Notifier,
StateProvider → NotifierProvider with simple notifier, FamilyAsyncNotifier
removed in Riverpod 3 (replaced with constructor-arg pattern), and rename
.valueOrNull → .value throughout all providers and screens.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>