UI Phase 2 (L0): shared layout primitives + chrome standardization

Extract four shared layout widgets from the best existing implementations and
adopt them across list/overview screens, deleting duplicated inline code.
Layout/consistency only — no behavior change.

New primitives (lib/widgets/):
- app_section_header.dart  — AppSectionHeader (azure accent bar + uppercase
  telemetry label; promoted from the dashboard's _sectionTitle).
- app_metric_card.dart     — AppMetricCard (uppercase label + mono value on a
  flat hairline surface; unifies KPI/stat tiles).
- app_status_summary.dart  — AppStatusSummaryRow/Item/Chip (dot + count + label,
  selectable; semantic AppStatusColors).
- app_filter_bar.dart      — AppFilterBar (responsive filter-row chrome).

Adopted / de-duplicated:
- Dashboard: _MetricCard now wraps AppMetricCard; section titles use
  AppSectionHeader (removed local _sectionTitle).
- Tickets / Tasks / ISR: three separate summary-chip implementations
  (_StatusSummaryCard x2, _SummaryChip) collapsed into AppStatusSummaryRow.
- Network Map overview: Sites/Devices tiles -> AppMetricCard (removed local
  _SummaryCard).
- Workforce: "Duty Schedules" header -> AppSectionHeader with trailing chip.

Verified: flutter analyze lib clean; flutter build web green; visual QA (tickets
+ ISR summary chips) in dark.

Co-Authored-By: claude-flow <ruv@ruv.net>

lib/screens/tasks/tasks_list_screen.dart

@@ -30,6 +30,7 @@ import '../../widgets/tasq_adaptive_list.dart';
 import '../../widgets/typing_dots.dart';
 import '../../theme/app_surfaces.dart';
 import '../../theme/app_status_colors.dart';
+import '../../widgets/app_status_summary.dart';
 import '../../utils/snackbar.dart';
 import '../../widgets/app_breakpoints.dart';
 import '../../widgets/app_page_header.dart';
@@ -1329,63 +1330,15 @@ class _StatusSummaryRow extends StatelessWidget {
     final entries = counts.entries.toList()
       ..sort((a, b) => a.key.compareTo(b.key));
 
-    return SingleChildScrollView(
-      scrollDirection: Axis.horizontal,
-      child: Row(
-        children: [
-          for (int i = 0; i < entries.length; i++) ...[
-            if (i > 0) const SizedBox(width: 8),
-            _StatusSummaryCard(
-              status: entries[i].key,
-              count: entries[i].value,
-            ),
-          ],
-        ],
-      ),
-    );
-  }
-}
-
-class _StatusSummaryCard extends StatelessWidget {
-  const _StatusSummaryCard({required this.status, required this.count});
-
-  final String status;
-  final int count;
-
-  @override
-  Widget build(BuildContext context) {
-    final swatch = AppStatusColors.of(context).byKind(_taskStatusKind(status));
-    final background = swatch.container;
-    final foreground = swatch.onContainer;
-    final label = status.replaceAll('_', ' ').toUpperCase();
-
-    return Material(
-      color: background,
-      borderRadius: BorderRadius.circular(AppSurfaces.of(context).chipRadius),
-      child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
-        child: Row(
-          mainAxisSize: MainAxisSize.min,
-          children: [
-            Text(
-              label,
-              style: Theme.of(context).textTheme.labelSmall?.copyWith(
-                color: foreground,
-                fontWeight: FontWeight.w600,
-                letterSpacing: 0.4,
-              ),
-            ),
-            const SizedBox(width: 6),
-            Text(
-              count.toString(),
-              style: Theme.of(context).textTheme.labelLarge?.copyWith(
-                color: foreground,
-                fontWeight: FontWeight.w700,
-              ),
-            ),
-          ],
-        ),
-      ),
+    return AppStatusSummaryRow(
+      items: [
+        for (final e in entries)
+          AppStatusSummaryItem(
+            label: e.key.replaceAll('_', ' '),
+            count: e.value,
+            kind: _taskStatusKind(e.key),
+          ),
+      ],
     );
   }
 }