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, 3 insertions, 3 deletions

diff --git a/DomainDig/IntegrationsView.swift b/DomainDig/IntegrationsView.swift
index 73f511a..163d4d1 100644
--- a/DomainDig/IntegrationsView.swift
+++ b/DomainDig/IntegrationsView.swift
@@ -52,7 +52,7 @@ struct IntegrationsSettingsView: View {
                                 if !target.isEnabled {
                                     Text("Disabled")
                                         .font(.caption2)
-                                        .foregroundStyle(.orange)
+                                        .foregroundStyle(Color(.statusWarning))
                                 }
                             }
                         }
@@ -158,7 +158,7 @@ private struct IntegrationDetailView: View {
                                     .foregroundStyle(.secondary)
 
                                 if let failureReason = record.failureReason {
-                                    let failureColor: Color = record.status == .skipped ? .secondary : .red
+                                    let failureColor: Color = record.status == .skipped ? .secondary : Color(.statusCritical)
                                     Text(failureReason)
                                         .font(.caption)
                                         .foregroundStyle(failureColor)
@@ -324,7 +324,7 @@ private struct IntegrationEditorView: View {
                 Section {
                     Text(validationMessage)
                         .font(.caption)
-                        .foregroundStyle(.red)
+                        .foregroundStyle(Color(.statusCritical))
                 }
             }
         }