feat(a11y): semantic colour system (#21 phase 1)

Replaces every hard-coded colour with semantic asset colours that adapt to
light, dark, and Increase Contrast. Dark mode stays locked, so this is a
pure refactor: the audit reports the same findings before and after.

The accent is now blue rather than cyan, per the tech/DNS theme.

Why custom values rather than the system palette: every system colour
fails WCAG AA in light mode. Measured on white — systemYellow 1.51:1,
systemOrange 2.20:1, systemGreen 2.22:1, systemCyan 2.54:1, systemRed
3.55:1. All of them pass in dark mode, which is why the dark-locked app
looked fine, and why unlocking light mode was never a matter of deleting
.preferredColorScheme(.dark). Every new value clears 4.5:1 as text on its
page, its card, and its own 16% badge tint — the way AppStatusBadgeView
actually draws it.

The accent needed splitting in two. As text on a dark background it must
be light; as a fill behind a white label it must be dark. #4DA3FF reads
8.00:1 as text on black but 2.63:1 behind white text, so StatusInfo /
AccentColor cover the foreground role and AccentFill covers
.borderedProminent. AppOnAccent is the label colour for a solid fill and
flips by scheme.

Colours live in Shared/Colors.xcassets rather than the app catalog: the
Shared folder is already a synchronized group in all three targets, so
the widget and share extension pick the palette up with no project-file
surgery. AccentColor stays in the app catalog as the global tint — and is
now actually defined, having been an empty colorset that silently left
system controls rendering in stock blue while custom chrome used cyan.

Two deliberate visual changes: orange folds into StatusWarning and pink
into StatusCritical. They encoded the same severity as the colours they
now share, and both sites also carry a text label.

Audit findings drop 15 to 14, and one of the originals turned out to be
a phantom: the Inspect contrast failure was the Run button in its
disabled state, which WCAG 1.4.3 exempts. testInspectScreen now types a
domain first so the audit measures an enabled control. Findings also
carry the offending element now, so the remaining clipped-text items name
themselves ("No Portfolio Yet", "Search domains") instead of being
anonymous.

1 files changed, 9 insertions, 9 deletions

diff --git a/DomainDig/WorkflowsView.swift b/DomainDig/WorkflowsView.swift
index ce889fb..2195af5 100644
--- a/DomainDig/WorkflowsView.swift
+++ b/DomainDig/WorkflowsView.swift
@@ -24,13 +24,13 @@ struct WorkflowsView: View {
                         .font(appDensity.font(.caption))
                         .foregroundStyle(.secondary)
                 }
-                .listRowBackground(Color(.systemGray6).opacity(0.5))
+                .listRowBackground(Color(.appSurface))
             }
 
             workflowContent
         }
         .scrollContentBackground(.hidden)
-        .background(Color.black)
+        .background(Color(.appBackground))
         .refreshable {
             await viewModel.refreshWorkflowList()
         }
@@ -73,7 +73,7 @@ struct WorkflowsView: View {
                         value: Double(viewModel.batchCompletedCount),
                         total: Double(max(viewModel.batchTotalCount, 1))
                     )
-                    .tint(.cyan)
+                    .tint(Color(.statusInfo))
 
                     HStack {
                         Text(viewModel.batchProgressLabel)
@@ -91,7 +91,7 @@ struct WorkflowsView: View {
                 }
                 .padding(.vertical, 4)
             }
-            .listRowBackground(Color(.systemGray6).opacity(0.5))
+            .listRowBackground(Color(.appSurface))
         }
 
         if viewModel.workflows.isEmpty {
@@ -104,7 +104,7 @@ struct WorkflowsView: View {
                     showsCardBackground: false
                 )
             }
-            .listRowBackground(Color(.systemGray6).opacity(0.5))
+            .listRowBackground(Color(.appSurface))
         } else {
             ForEach(viewModel.workflows) { workflow in
                 NavigationLink {
@@ -112,7 +112,7 @@ struct WorkflowsView: View {
                 } label: {
                     WorkflowRowView(workflow: workflow)
                 }
-                .listRowBackground(Color(.systemGray6).opacity(0.5))
+                .listRowBackground(Color(.appSurface))
             }
             .onDelete { offsets in
                 let workflows = offsets.map { viewModel.workflows[$0] }
@@ -133,7 +133,7 @@ private struct WorkflowRowView: View {
                 if workflow.collaboration?.isShared == true {
                     Image(systemName: "person.2.fill")
                         .font(.caption2)
-                        .foregroundStyle(.cyan)
+                        .foregroundStyle(Color(.statusInfo))
                 }
                 Text(workflow.name)
                     .font(appDensity.font(.callout, design: .default, weight: .semibold))
@@ -335,7 +335,7 @@ struct WorkflowDetailView: View {
                     }
                 }
                 .scrollContentBackground(.hidden)
-                .background(Color.black)
+                .background(Color(.appBackground))
                 .navigationTitle(workflow.name)
                 .toolbar {
                     if !workflow.domains.isEmpty {
@@ -640,7 +640,7 @@ struct WorkflowBulkAddSheet: View {
                                     .foregroundStyle(.primary)
                                 Spacer()
                                 Image(systemName: selectedDomains.contains(domain) ? "checkmark.circle.fill" : "circle")
-                                    .foregroundStyle(selectedDomains.contains(domain) ? .cyan : .secondary)
+                                    .foregroundStyle(selectedDomains.contains(domain) ? Color(.statusInfo) : .secondary)
                             }
                         }
                         .buttonStyle(.plain)