fix: restore offline queue for captures, drain via chat on retry

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>

lib/providers/capture_work_queue_provider.dart

@@ -2,6 +2,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../core/exceptions.dart';
 import 'api_client_provider.dart';
+import 'capture_queue_provider.dart';
 import 'chat_provider.dart';
 
 /// Outcome of a single capture attempt — consumed by the UI for snackbars.
@@ -63,11 +64,13 @@ class CaptureWorkQueueNotifier extends Notifier<List<String>> {
           ref.read(captureResultProvider.notifier).state =
               const CaptureResult('Sent to Fabled.');
         } on NetworkException catch (_) {
+          // Persist to offline queue and stop draining — still offline.
+          await ref.read(captureQueueProvider.notifier).enqueue(text);
           state = state.length > 1 ? state.sublist(1) : [];
           ref.read(captureResultProvider.notifier).state = const CaptureResult(
-            "You're offline — message not sent.",
-            isError: true,
+            "You're offline — capture saved and will retry automatically.",
           );
+          break;
         } on AppException catch (e) {
           state = state.length > 1 ? state.sublist(1) : [];
           ref.read(captureResultProvider.notifier).state =