feat(dashboard): GuruConnect v2 operator console (pass 1)

React + Vite + TypeScript SPA: scaffold, operations-terminal design
system, Bearer-token auth, and the Machines view.

- Design system: OKLCH-tinted dark theme (ink-slate + signal-cyan),
  Hanken Grotesk + JetBrains Mono, status-color language
  (online/offline/granted/pending/denied/not_required), motion with
  prefers-reduced-motion honored.
- Auth: token in sessionStorage via ref (never React state), protected
  routes, 401 session teardown, admin-gated per-agent-key UI.
- Machines view: data table (sticky header, keyboard-activated rows,
  skeleton loading, actionable empty/error states), non-blocking detail
  drawer, delete confirm, admin key management with copy-once reveal.
- UI primitives: Modal (focus trap + inert + portal + dialogStack),
  Drawer, Table, Badge/StatusDot, toast, states.
- Typed API client normalizing the two error-envelope shapes.

Passed Code Review (no blockers), impeccable critique-and-polish, and
local gates (tsc/lint/build green). Dev-only Vite proxy to :3002.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

dashboard/src/components/layout/PageHeader.tsx

@@ -0,0 +1,21 @@
+import type { ReactNode } from "react";
+
+interface PageHeaderProps {
+  title: string;
+  subtitle?: ReactNode;
+  /** Primary action slot, right-aligned. */
+  actions?: ReactNode;
+}
+
+/** Standard page title block with an action slot. */
+export function PageHeader({ title, subtitle, actions }: PageHeaderProps) {
+  return (
+    <div className="page__header">
+      <div className="page__titles">
+        <h1>{title}</h1>
+        {subtitle && <div className="page__subtitle">{subtitle}</div>}
+      </div>
+      {actions && <div className="page__actions">{actions}</div>}
+    </div>
+  );
+}