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, 55 insertions, 8 deletions

diff --git a/DomainDig/DomainDigUI.swift b/DomainDig/DomainDigUI.swift
index 7d99e4e..3aec259 100644
--- a/DomainDig/DomainDigUI.swift
+++ b/DomainDig/DomainDigUI.swift
@@ -120,6 +120,53 @@ extension EnvironmentValues {
     }
 }
 
+/// A status colour pairing: the foreground and the surface it sits on.
+///
+/// These travel together because they cannot be derived from one another. The
+/// badge fill used to be `foreground.opacity(0.16)`, which forced every
+/// foreground dark enough to stay legible against its own wash — that is how the
+/// light palette ended up olive-and-mud rather than amber-and-green. Decoupling
+/// them lets the foregrounds stay fully saturated.
+///
+/// See `Docs/ACCESSIBILITY.md` for the measured ratios.
+enum AppStatusTone {
+    case positive
+    case warning
+    case critical
+    case info
+    case neutral
+
+    var foreground: Color {
+        switch self {
+        case .positive:
+            return Color(.statusPositive)
+        case .warning:
+            return Color(.statusWarning)
+        case .critical:
+            return Color(.statusCritical)
+        case .info:
+            return Color(.statusInfo)
+        case .neutral:
+            return Color(.statusNeutral)
+        }
+    }
+
+    var surface: Color {
+        switch self {
+        case .positive:
+            return Color(.statusPositiveSurface)
+        case .warning:
+            return Color(.statusWarningSurface)
+        case .critical:
+            return Color(.statusCriticalSurface)
+        case .info:
+            return Color(.statusInfoSurface)
+        case .neutral:
+            return Color(.statusNeutralSurface)
+        }
+    }
+}
+
 struct AppStatusBadgeModel: Equatable {
     let title: String
     let systemImage: String?
@@ -131,9 +178,9 @@ enum AppStatusFactory {
     static func availability(_ status: DomainAvailabilityStatus?) -> AppStatusBadgeModel {
         switch status {
         case .available:
-            return .init(title: "Available", systemImage: "checkmark.circle.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositive).opacity(0.16))
+            return .init(title: "Available", systemImage: "checkmark.circle.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositiveSurface))
         case .registered:
-            return .init(title: "Registered", systemImage: "circle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarning).opacity(0.16))
+            return .init(title: "Registered", systemImage: "circle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarningSurface))
         case .unknown, .none:
             return .init(title: "Unknown", systemImage: "questionmark.circle", foregroundColor: Color(.appTextSecondary), backgroundColor: Color(.appSurfaceElevated))
         }
@@ -141,12 +188,12 @@ enum AppStatusFactory {
 
     static func tls(sslInfo: SSLCertificateInfo?, error: String?) -> AppStatusBadgeModel {
         if error != nil || sslInfo == nil {
-            return .init(title: "Invalid", systemImage: "xmark.octagon.fill", foregroundColor: Color(.statusCritical), backgroundColor: Color(.statusCritical).opacity(0.16))
+            return .init(title: "Invalid", systemImage: "xmark.octagon.fill", foregroundColor: Color(.statusCritical), backgroundColor: Color(.statusCriticalSurface))
         }
         if let sslInfo, sslInfo.daysUntilExpiry <= 14 {
-            return .init(title: "Expiring", systemImage: "exclamationmark.triangle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarning).opacity(0.16))
+            return .init(title: "Expiring", systemImage: "exclamationmark.triangle.fill", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarningSurface))
         }
-        return .init(title: "Valid", systemImage: "lock.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositive).opacity(0.16))
+        return .init(title: "Valid", systemImage: "lock.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositiveSurface))
     }
 
     static func email(_ result: EmailSecurityResult?, error: String?) -> AppStatusBadgeModel {
@@ -157,9 +204,9 @@ enum AppStatusFactory {
         let foundCount = [result.spf.found, result.dmarc.found, result.dkim.found].filter { $0 }.count
         switch foundCount {
         case 3:
-            return .init(title: "Secure", systemImage: "checkmark.shield.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositive).opacity(0.16))
+            return .init(title: "Secure", systemImage: "checkmark.shield.fill", foregroundColor: Color(.statusPositive), backgroundColor: Color(.statusPositiveSurface))
         case 1, 2:
-            return .init(title: "Partial", systemImage: "shield.lefthalf.filled", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarning).opacity(0.16))
+            return .init(title: "Partial", systemImage: "shield.lefthalf.filled", foregroundColor: Color(.statusWarning), backgroundColor: Color(.statusWarningSurface))
         default:
             return .init(title: "Missing", systemImage: "minus.circle", foregroundColor: Color(.appTextSecondary), backgroundColor: Color(.appSurfaceElevated))
         }
@@ -170,7 +217,7 @@ enum AppStatusFactory {
             return .init(title: "Unchanged", systemImage: "circle", foregroundColor: Color(.appTextSecondary), backgroundColor: Color(.appSurfaceElevated))
         }
         if summary.hasChanges {
-            return .init(title: "Changed", systemImage: "arrow.triangle.2.circlepath", foregroundColor: Color(.statusInfo), backgroundColor: Color(.statusInfo).opacity(0.16))
+            return .init(title: "Changed", systemImage: "arrow.triangle.2.circlepath", foregroundColor: Color(.statusInfo), backgroundColor: Color(.statusInfoSurface))
         }
         return .init(title: "Unchanged", systemImage: "checkmark.circle", foregroundColor: Color(.appTextSecondary), backgroundColor: Color(.appSurfaceElevated))
     }