feat(ui): refine gem-blue acrylic palette and focus borders

Derive the gem-blue palette with OKLCH tonal and complementary-color
rules while preserving acrylic opacity, blur and surface hierarchy.

Darker focus tokens exposed stacked field rings, fallback outlines and
persistent basemap selection rings. Keep fallback focus styles in the
base layer and use one themed field boundary or inset card stroke.
Preserve keyboard focus, invalid states and native input semantics.

Add browser regression coverage for pointer and keyboard focus, all
basemap presentations, narrow layouts and rendered contrast.

Validation in an isolated checkout: pnpm lint, pnpm typecheck,
pnpm test (393 tests), focused browser suites and pnpm build.

src/features/workbench/components/agent-task-ticker.tsx

@@ -307,7 +307,7 @@ export function AgentTaskTicker({
                     key={runningCondition.id}
                     className={cn(
                       "block h-1.5 w-1.5 rounded-sm transition-colors duration-150",
-                      index === activeIndicatorIndex ? "bg-blue-600" : "bg-slate-300"
+                      index === activeIndicatorIndex ? "bg-[var(--action-blue)]" : "bg-slate-300"
                     )}
                   />
                 ))}
@@ -391,7 +391,7 @@ function TickerTaskCardContent({ view }: { view: TickerStackCard["view"] }) {
       <div className="grid h-full grid-cols-[14px_minmax(0,1fr)] items-center gap-3 pr-4">
         <TickerStatusDot progressValue={view.progressValue} />
         <div className="min-w-0">
-          <span className="block truncate text-[13px] font-semibold leading-5 text-slate-500">
+          <span className="block truncate text-[13px] font-semibold leading-5 text-[var(--ink-muted)]">
             {view.title}
           </span>
           {view.progressValue !== undefined ? (
@@ -407,7 +407,7 @@ function TickerTaskCardContent({ view }: { view: TickerStackCard["view"] }) {
       <TickerStatusDot progressValue={view.progressValue} />
       <div className="flex min-w-0 flex-col justify-center">
         <div className="min-w-0 pr-1">
-          <span className="block truncate text-[13px] font-semibold leading-4 text-slate-500">
+          <span className="block truncate text-[13px] font-semibold leading-4 text-[var(--ink-muted)]">
             {view.title}
           </span>
         </div>
@@ -417,7 +417,7 @@ function TickerTaskCardContent({ view }: { view: TickerStackCard["view"] }) {
               {view.currentStep.title}
             </span>
             <span className="h-1 w-1 rounded-full bg-slate-300" aria-hidden="true" />
-            <span className="min-w-0 truncate text-[13px] font-medium leading-5 text-slate-500">
+            <span className="min-w-0 truncate text-[13px] font-medium leading-5 text-[var(--ink-muted)]">
               {view.currentStep.detail}
             </span>
           </div>
@@ -441,7 +441,7 @@ function TickerProgressBar({
     <div
       className={cn(
         "mt-0.5 h-0.5 overflow-hidden rounded-full",
-        muted ? "bg-slate-200/60" : "bg-slate-200/80"
+        muted ? "bg-[var(--surface-divider)]/60" : "bg-[var(--surface-divider)]/80"
       )}
       aria-hidden="true"
     >