fix(a11y): rebalance the light palette so hues survive

Reported as "colors seem muted and hard to see on light mode", and
correct. The light palette optimised contrast and produced mud: #7A5600
reads olive rather than amber, #146C2E bottle-dark rather than green.
Contrast passed while the UI got harder to read, because hue identity is
what distinguishes warning from critical at a glance.

Two causes, both fixed.

Every foreground was required to clear 4.5:1 against its own 16% badge
tint — the harshest surface it ever sits on — which pushed each colour
about 20% darker than the common case needed. Most of what is actually on
screen is plain text on a card, with far more headroom. The fill is now
decoupled from the foreground: AppStatusTone carries a foreground and a
surface authored independently, with matching …Surface colorsets, so a
foreground no longer has to survive a wash of itself. Every status
foreground is now fully saturated.

And warning was yellow. Yellow cannot stay yellow at a lightness low
enough to pass 4.5:1 on white — it becomes olive. That is colorimetric,
not a tuning problem. Warning is now orange: #AD5100 light, #FF9F0A dark.

New light values: positive #008035, warning #AD5100, critical #CC0700.
Worst-case ratios 4.54–6.76 across page, card, and surface in both
schemes. Audit findings are unchanged — light 21, dark 18 — so the
vividness costs nothing.

Also picks up a literal .blue missed in phase 1: DomainDiffItem's
low-severity change colour, which the phase 1 sweep did not cover because
its pattern listed only cyan/yellow/green/red/orange/pink.

1 files changed, 12 insertions, 12 deletions

diff --git a/DomainDig/DashboardView.swift b/DomainDig/DashboardView.swift
index 8d41ccb..16c4478 100644
--- a/DomainDig/DashboardView.swift
+++ b/DomainDig/DashboardView.swift
@@ -237,20 +237,20 @@ struct DashboardView: View {
         let criticalCount = states.filter { $0.health == .critical }.count
         let warningCount = states.filter { $0.health == .warning }.count
         let title: String
-        let color: Color
+        let tone: AppStatusTone
         let systemImage: String
 
         if criticalCount > 0 {
             title = "\(criticalCount) critical"
-            color = Color(.statusCritical)
+            tone = .critical
             systemImage = "exclamationmark.octagon.fill"
         } else if warningCount > 0 {
             title = "\(warningCount) warning"
-            color = Color(.statusWarning)
+            tone = .warning
             systemImage = "exclamationmark.triangle.fill"
         } else {
             title = "Healthy"
-            color = Color(.statusPositive)
+            tone = .positive
             systemImage = "checkmark.circle.fill"
         }
 
@@ -258,8 +258,8 @@ struct DashboardView: View {
             model: .init(
                 title: title,
                 systemImage: systemImage,
-                foregroundColor: color,
-                backgroundColor: color.opacity(0.16)
+                foregroundColor: tone.foreground,
+                backgroundColor: tone.surface
             )
         )
     }
@@ -331,11 +331,11 @@ private struct PortfolioAttentionRow: View {
     private var badgeModel: AppStatusBadgeModel {
         switch item.health {
         case .healthy:
-            return .init(title: "Healthy", systemImage: "checkmark.circle.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositive).opacity(0.16))
+            return .init(title: "Healthy", systemImage: "checkmark.circle.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositiveSurface))
         case .warning:
-            return .init(title: "Warning", systemImage: "exclamationmark.triangle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarning).opacity(0.16))
+            return .init(title: "Warning", systemImage: "exclamationmark.triangle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarningSurface))
         case .critical:
-            return .init(title: "Critical", systemImage: "exclamationmark.octagon.fill", foregroundColor: Color(.statusCritical), backgroundColor: Color(.statusCritical).opacity(0.16))
+            return .init(title: "Critical", systemImage: "exclamationmark.octagon.fill", foregroundColor: Color(.statusCritical), backgroundColor: Color(.statusCriticalSurface))
         }
     }
 }
@@ -370,11 +370,11 @@ private struct PortfolioExpiryRow: View {
     private var badgeModel: AppStatusBadgeModel {
         switch state.certificateExpiryState {
         case .none:
-            return .init(title: "Healthy", systemImage: "lock.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositive).opacity(0.16))
+            return .init(title: "Healthy", systemImage: "lock.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositiveSurface))
         case .warning:
-            return .init(title: "Warning", systemImage: "exclamationmark.triangle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarning).opacity(0.16))
+            return .init(title: "Warning", systemImage: "exclamationmark.triangle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarningSurface))
         case .critical:
-            return .init(title: "Critical", systemImage: "xmark.octagon.fill", foregroundColor: Color(.statusCritical), backgroundColor: Color(.statusCritical).opacity(0.16))
+            return .init(title: "Critical", systemImage: "xmark.octagon.fill", foregroundColor: Color(.statusCritical), backgroundColor: Color(.statusCriticalSurface))
         }
     }
 }