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/network_map/network_map_overview_screen.dart

@@ -7,6 +7,7 @@ import '../../providers/network_map/network_devices_provider.dart';
 import '../../providers/network_map/network_sites_provider.dart';
 import '../../providers/profile_provider.dart';
 import '../../utils/snackbar.dart';
+import '../../widgets/app_metric_card.dart';
 import '../../widgets/app_page_header.dart';
 import '../../widgets/app_state_view.dart';
 import '../../widgets/responsive_body.dart';
@@ -167,41 +168,24 @@ class _SummaryRow extends StatelessWidget {
   Widget build(BuildContext context) {
     return Row(
       children: [
-        Expanded(child: _SummaryCard(label: 'Sites', value: siteCount.toString(), icon: Icons.location_city_outlined)),
-        const SizedBox(width: 12),
-        Expanded(child: _SummaryCard(label: 'Devices', value: deviceCount.toString(), icon: Icons.devices_outlined)),
-      ],
-    );
-  }
-}
-
-class _SummaryCard extends StatelessWidget {
-  const _SummaryCard({required this.label, required this.value, required this.icon});
-  final String label;
-  final String value;
-  final IconData icon;
-
-  @override
-  Widget build(BuildContext context) {
-    final tt = Theme.of(context).textTheme;
-    final cs = Theme.of(context).colorScheme;
-    return Card(
-      child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
-        child: Row(
-          children: [
-            Icon(icon, color: cs.primary),
-            const SizedBox(width: 12),
-            Column(
-              crossAxisAlignment: CrossAxisAlignment.start,
-              children: [
-                Text(label, style: tt.labelSmall?.copyWith(color: cs.onSurfaceVariant)),
-                Text(value, style: tt.headlineSmall?.copyWith(fontWeight: FontWeight.w700)),
-              ],
-            ),
-          ],
+        Expanded(
+          child: AppMetricCard(
+            title: 'Sites',
+            value: siteCount.toString(),
+            icon: Icons.location_city_outlined,
+            animateValue: false,
+          ),
         ),
-      ),
+        const SizedBox(width: 12),
+        Expanded(
+          child: AppMetricCard(
+            title: 'Devices',
+            value: deviceCount.toString(),
+            icon: Icons.devices_outlined,
+            animateValue: false,
+          ),
+        ),
+      ],
     );
   }
 }