feat(notifications): day sheet notification types

Add daySheetId field to NotificationItem model (Brick-managed), extract
notificationTitle/notificationIcon to top-level testable functions, add
five day-sheet notification cases, and wire tap/banner routing for
day-sheet detail and approvals tab.
Co-Authored-By: claude-flow <ruv@ruv.net>

lib/brick/db/20260928065256.migration.dart

@@ -0,0 +1,36 @@
+// GENERATED CODE EDIT WITH CAUTION
+// THIS FILE **WILL NOT** BE REGENERATED
+// This file should be version controlled and can be manually edited.
+part of 'schema.g.dart';
+
+// While migrations are intelligently created, the difference between some commands, such as
+// DropTable vs. RenameTable, cannot be determined. For this reason, please review migrations after
+// they are created to ensure the correct inference was made.
+
+// The migration version must **always** mirror the file name
+
+const List<MigrationCommand> _migration_20260928065256_up = [
+  InsertColumn('day_sheet_id', Column.varchar, onTable: 'NotificationItem')
+];
+
+const List<MigrationCommand> _migration_20260928065256_down = [
+  DropColumn('day_sheet_id', onTable: 'NotificationItem')
+];
+
+//
+// DO NOT EDIT BELOW THIS LINE
+//
+
+@Migratable(
+  version: '20260928065256',
+  up: _migration_20260928065256_up,
+  down: _migration_20260928065256_down,
+)
+class Migration20260928065256 extends Migration {
+  const Migration20260928065256()
+    : super(
+        version: 20260928065256,
+        up: _migration_20260928065256_up,
+        down: _migration_20260928065256_down,
+      );
+}