feat(a11y): color independence, reduce motion, reduce transparency (#21 phase 5)

Audit unchanged at 11 dark / 14 light — expected, as none of these
settings are exercised by performAccessibilityAudit, and simctl can
toggle only Increase Contrast, not Differentiate Without Color, Reduce
Motion, or Reduce Transparency. Correct by construction and build-clean;
runtime behaviour is verified in the Phase 6 manual pass.

Color independence:

- Widget status is now an SF Symbol (checkmark.circle.fill /
  exclamationmark.triangle.fill / exclamationmark.octagon.fill), the same
  vocabulary as the in-app badges, replacing a silent colour-only dot on
  both the domain rows and the small-view count pills. Status now survives
  greyscale and reads consistently across surfaces.
- Under accessibilityDifferentiateWithoutColor: the Dashboard
  summary-card dot becomes a per-filter symbol, the selected quick-filter
  chip gains a checkmark and a border (selection was fill-colour only, and
  also gains the .isSelected trait), and LabeledValueRow prefixes a
  warning/failure symbol. All gated on the setting so the default UI stays
  uncluttered.

Reduce motion: all five withAnimation/.animation sites now pass nil under
accessibilityReduceMotion — AppCopyButton's check cross-fade,
CollapsibleSectionView's expand/collapse, TimelineDiffView's scroll, and
WatchlistView's list reorder.

Reduce transparency: the single .thinMaterial capsule falls back to an
opaque AppSurfaceElevated fill under accessibilityReduceTransparency.

The SweepActivityController item from the plan is dropped: it is pure
ActivityKit lifecycle with no animation, confirmed back in the issue
triage.

1 files changed, 21 insertions, 8 deletions

diff --git a/DomainDigWidget/DomainDigPortfolioWidget.swift b/DomainDigWidget/DomainDigPortfolioWidget.swift
index 66002c5..45772e3 100644
--- a/DomainDigWidget/DomainDigPortfolioWidget.swift
+++ b/DomainDigWidget/DomainDigPortfolioWidget.swift
@@ -97,16 +97,18 @@ struct DomainDigWidgetView: View {
             Spacer(minLength: 0)
 
             HStack(spacing: 10) {
-                countPill(data.healthyCount, Color(.statusPositive), "healthy")
-                countPill(data.warningCount, Color(.statusWarning), "warning")
-                countPill(data.criticalCount, Color(.statusCritical), "critical")
+                countPill(data.healthyCount, .healthy, "healthy")
+                countPill(data.warningCount, .warning, "warning")
+                countPill(data.criticalCount, .critical, "critical")
             }
         }
     }
 
-    private func countPill(_ value: Int, _ color: Color, _ label: String) -> some View {
+    private func countPill(_ value: Int, _ status: DomainDigWidgetStatus, _ label: String) -> some View {
         HStack(spacing: 3) {
-            Circle().fill(color).frame(width: 7, height: 7)
+            Image(systemName: symbol(for: status))
+                .font(.caption2)
+                .foregroundStyle(color(for: status))
             Text("\(value)").font(.caption).fontWeight(.medium)
         }
         // A coloured dot and a number say nothing on their own.
@@ -163,9 +165,9 @@ struct DomainDigWidgetView: View {
 
     private func domainRow(_ domain: DomainDigWidgetDomain) -> some View {
         HStack(spacing: 6) {
-            Circle()
-                .fill(color(for: domain.status))
-                .frame(width: 8, height: 8)
+            Image(systemName: symbol(for: domain.status))
+                .font(.caption2)
+                .foregroundStyle(color(for: domain.status))
             if domain.isPinned {
                 Image(systemName: "pin.fill")
                     .font(.caption2)
@@ -219,4 +221,15 @@ struct DomainDigWidgetView: View {
         case .critical: return Color(.statusCritical)
         }
     }
+
+    /// Same symbol vocabulary as the in-app badges, so status survives without
+    /// colour (Differentiate Without Color, greyscale, colour-blind viewers) and
+    /// reads consistently across surfaces.
+    private func symbol(for status: DomainDigWidgetStatus) -> String {
+        switch status {
+        case .healthy: return "checkmark.circle.fill"
+        case .warning: return "exclamationmark.triangle.fill"
+        case .critical: return "exclamationmark.octagon.fill"
+        }
+    }
 }