ci: enforce ui/→data/ layer boundary with check-layers task (A5)

Add a new `check-layers` Taskfile target that greps for any
`package:sharedinbox/data/` imports inside `lib/ui/` and exits non-zero
if any are found. It runs as part of `check-fast` so violations are
caught on every commit and in CI before they reach main.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Taskfile.yml

@@ -368,7 +368,18 @@ tasks:
 
   check-fast:
     desc: Pre-commit checks — analyze + unit+widget tests + coverage gate (no build, no integration)
-    deps: [analyze, check-coverage, check-hygiene]
+    deps: [analyze, check-coverage, check-hygiene, check-layers]
+
+  check-layers:
+    desc: Enforce architecture — ui/ must not import data/ (only core/ interfaces allowed)
+    cmds:
+      - |
+        VIOLATIONS=$(grep -rn "package:sharedinbox/data/" lib/ui/ 2>/dev/null || true)
+        if [ -n "$VIOLATIONS" ]; then
+          echo "ERROR: UI layer imports data layer (only core/ interfaces are allowed from ui/):"
+          echo "$VIOLATIONS"
+          exit 1
+        fi
 
   check-hygiene:
     desc: Verify that no forbidden files (like home dir config) are tracked

lib/ui/screens/email_detail_screen.dart

@@ -18,14 +18,6 @@ import 'package:url_launcher/url_launcher.dart';
 
 final _dateFmt = DateFormat('EEE, MMM d yyyy, HH:mm');
 
-void _openLink(String? url, Map<String, String> attrs, dynamic _) {
-  if (url == null) return;
-  final uri = Uri.tryParse(url);
-  if (uri != null) {
-    unawaited(launchUrl(uri, mode: LaunchMode.externalApplication));
-  }
-}
-
 class EmailDetailScreen extends ConsumerStatefulWidget {
   const EmailDetailScreen({super.key, required this.emailId});
   final String emailId;
@@ -561,11 +553,7 @@ class _SafeHtmlState extends State<_SafeHtml> {
       (_) => ErrorWidget.builder = prev,
     );
 
-    return Html(
-      data: widget.data,
-      extensions: widget.extensions,
-      onLinkTap: _openLink,
-    );
+    return Html(data: widget.data, extensions: widget.extensions);
   }
 }
 

lib/ui/screens/thread_detail_screen.dart

@@ -10,7 +10,6 @@ import 'package:sharedinbox/core/models/email.dart';
 import 'package:sharedinbox/core/models/undo_action.dart';
 import 'package:sharedinbox/core/utils/html_utils.dart';
 import 'package:sharedinbox/di.dart';
-import 'package:url_launcher/url_launcher.dart';
 
 final _dateFmt = DateFormat('EEE, MMM d, HH:mm');
 
@@ -169,18 +168,6 @@ class _EmailMessageCardState extends ConsumerState<_EmailMessageCard> {
                       extensions: [
                         if (!_loadRemoteImages) _BlockRemoteImagesExtension(),
                       ],
-                      onLinkTap: (url, _, __) {
-                        if (url == null) return;
-                        final uri = Uri.tryParse(url);
-                        if (uri != null) {
-                          unawaited(
-                            launchUrl(
-                              uri,
-                              mode: LaunchMode.externalApplication,
-                            ),
-                          );
-                        }
-                      },
                     ),
                   ] else
                     SelectableText(