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/widgets/app_status_summary.dart

@@ -0,0 +1,126 @@
+import 'package:flutter/material.dart';
+
+import '../theme/app_status_colors.dart';
+import '../theme/app_surfaces.dart';
+
+/// One entry in an [AppStatusSummaryRow].
+class AppStatusSummaryItem {
+  const AppStatusSummaryItem({
+    required this.label,
+    required this.count,
+    required this.kind,
+    this.selected = false,
+    this.onTap,
+  });
+
+  final String label;
+  final int count;
+  final StatusKind kind;
+
+  /// Emphasized (filled) when true — used for the active filter.
+  final bool selected;
+
+  /// When set, the chip is tappable (e.g. to filter the list by this status).
+  final VoidCallback? onTap;
+}
+
+/// A horizontally-scrollable row of status-count chips — the single shared
+/// "count-by-status" summary used above entity lists (unifies the separate
+/// tickets / tasks / ISR summary-chip implementations).
+class AppStatusSummaryRow extends StatelessWidget {
+  const AppStatusSummaryRow({
+    super.key,
+    required this.items,
+    this.padding = EdgeInsets.zero,
+  });
+
+  final List<AppStatusSummaryItem> items;
+  final EdgeInsetsGeometry padding;
+
+  @override
+  Widget build(BuildContext context) {
+    if (items.isEmpty) return const SizedBox.shrink();
+    return SingleChildScrollView(
+      scrollDirection: Axis.horizontal,
+      padding: padding,
+      child: Row(
+        children: [
+          for (var i = 0; i < items.length; i++) ...[
+            if (i > 0) const SizedBox(width: 8),
+            AppStatusSummaryChip(item: items[i]),
+          ],
+        ],
+      ),
+    );
+  }
+}
+
+/// A single status-count chip: a status dot + bold count + label. Filled with
+/// the status tone when [AppStatusSummaryItem.selected], subtle otherwise.
+class AppStatusSummaryChip extends StatelessWidget {
+  const AppStatusSummaryChip({super.key, required this.item});
+
+  final AppStatusSummaryItem item;
+
+  @override
+  Widget build(BuildContext context) {
+    final cs = Theme.of(context).colorScheme;
+    final tt = Theme.of(context).textTheme;
+    final swatch = AppStatusColors.of(context).byKind(item.kind);
+    final radius = AppSurfaces.of(context).chipRadius;
+
+    final bg = item.selected ? swatch.container : cs.surfaceContainerHighest;
+    final labelColor =
+        item.selected ? swatch.onContainer : cs.onSurfaceVariant;
+    final countColor = item.selected ? swatch.onContainer : cs.onSurface;
+
+    final chip = AnimatedContainer(
+      duration: const Duration(milliseconds: 200),
+      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+      decoration: BoxDecoration(
+        color: bg,
+        borderRadius: BorderRadius.circular(radius),
+        border: Border.all(
+          color: item.selected ? Colors.transparent : cs.outlineVariant,
+        ),
+      ),
+      child: Row(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Container(
+            width: 8,
+            height: 8,
+            decoration: BoxDecoration(
+              color: swatch.color,
+              shape: BoxShape.circle,
+            ),
+          ),
+          const SizedBox(width: 8),
+          Text(
+            item.count.toString(),
+            style: tt.labelLarge?.copyWith(
+              color: countColor,
+              fontWeight: FontWeight.w700,
+            ),
+          ),
+          const SizedBox(width: 6),
+          Text(
+            item.label.toUpperCase(),
+            style: tt.labelSmall?.copyWith(
+              color: labelColor,
+              fontWeight: FontWeight.w600,
+              letterSpacing: 0.4,
+            ),
+          ),
+        ],
+      ),
+    );
+
+    if (item.onTap == null) return chip;
+    return InkWell(
+      onTap: item.onTap,
+      borderRadius: BorderRadius.circular(radius),
+      child: chip,
+    );
+  }
+}