Route todo's snackbars through the shared showToast/showError

The package shipped feedback helpers while todo still had a private
_showSnack and a raw SnackBar in note_editor -- exactly the duplication
the extraction was meant to end, left live in a repo that had just
adopted the package.

Two deliberate behaviour changes come with it: the duration goes 2s ->
3s for toasts and 5s for errors (an error the user missed is an error
they will hit again), and messages now replace rather than queue, since
a queued snackbar describes an action the user moved on from seconds
ago. No test asserted on either, and the one snackbar assertion in the
suite checks that capture is *not* interrupted by one, which still holds.

Failures now read as failures: the mode-switch rejection in note_editor
and a failed sync in capture_screen use showError, while a successful
sync and the not-configured hint stay neutral toasts. Spending the danger
hue on routine confirmations is how a real failure becomes invisible.

Verified: flutter analyze clean, 308 tests pass at 100% coverage
(1964/1964). The release APK built and installed, but on-device
re-verification could not complete: the 23:00 night curfew removed the
package ~80ms after install, because dev.kuhy.todo is in the focus-mode
day WHITELIST but not NIGHT_WHITELIST. Enforcer working as designed, not
an app fault -- reverify after 05:00.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XS1m7b1piBtAL22USLW6jL

lib/ui/capture_screen.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'package:crdt_sync/crdt_sync.dart';
+import 'package:design_system/design_system.dart';
 import 'package:flutter/material.dart';
 import 'package:http/http.dart' as http;
 import 'package:todo/analytics/analytics_event.dart';
@@ -221,6 +222,7 @@ class _CaptureScreenState extends State<CaptureScreen>
         outcome.ok
             ? 'Synced: ${outcome.detail}'
             : 'Sync failed: ${outcome.detail}',
+        isError: !outcome.ok,
       );
     } finally {
       if (mounted) setState(() => _syncing = false);

lib/ui/capture_screen_sync.dart

@@ -64,11 +64,19 @@ extension _CaptureSyncBehaviour on _CaptureScreenState {
     );
   }
 
-  void _showSnack(String message) {
+  /// Shows transient feedback, if this screen is still mounted.
+  ///
+  /// Delegates to the shared helpers so the styling and the
+  /// replace-don't-queue behaviour match every other app; [isError] picks
+  /// the danger hue and the longer duration, because an error the user
+  /// missed is an error they will hit again.
+  void _showSnack(String message, {bool isError = false}) {
     if (!mounted) return;
-    ScaffoldMessenger.of(context).showSnackBar(
-      SnackBar(content: Text(message), duration: const Duration(seconds: 2)),
-    );
+    if (isError) {
+      showError(context, message);
+    } else {
+      showToast(context, message);
+    }
   }
 
   /// Reloads the persisted last-sync outcome so the status line survives a

lib/ui/note_editor.dart

@@ -1,3 +1,4 @@
+import 'package:design_system/design_system.dart';
 import 'package:flutter/material.dart';
 
 import 'package:todo/data/note.dart';
@@ -111,13 +112,9 @@ class _NoteEditorState extends State<NoteEditor> {
         case NoteEditorMode.guided:
           // raw -> guided: only if the edited text still fits the template.
           if (!_doc.tryAdoptGuided()) {
-            ScaffoldMessenger.of(context).showSnackBar(
-              const SnackBar(
-                content: Text(
-                  "Text doesn't match the template — staying in raw",
-                ),
-                duration: Duration(seconds: 2),
-              ),
+            showError(
+              context,
+              "Text doesn't match the template — staying in raw",
             );
             return;
           }

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 1.0.23+1
+version: 1.0.24+1
 
 environment:
   sdk: ^3.12.2