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/ui/toast-context.ts

@@ -0,0 +1,25 @@
+import { createContext, useContext } from "react";
+
+export type ToastTone = "success" | "error" | "info";
+
+export interface ToastItem {
+  id: number;
+  tone: ToastTone;
+  title: string;
+  message?: string;
+}
+
+export interface ToastApi {
+  success: (title: string, message?: string) => void;
+  error: (title: string, message?: string) => void;
+  info: (title: string, message?: string) => void;
+}
+
+export const ToastContext = createContext<ToastApi | null>(null);
+
+/** Imperative toast notifications. Auto-dismiss after a few seconds. */
+export function useToast(): ToastApi {
+  const ctx = useContext(ToastContext);
+  if (!ctx) throw new Error("useToast must be used within <ToastProvider>");
+  return ctx;
+}