feat(desktop): implement workspace foundation + desktop-client skeleton

Plan 0 (workspaces): add workspaces + workspace_memberships schema, extend
JWT/Actor/claims with primary_workspace_id, seed default workspace per tenant,
thread workspace_id through tenant monitoring quota.

Plan A (desktop skeleton): new Electron app (apps/desktop-client) with main/
preload/renderer, shared Vue component package (packages/ui-shared), and server
surface — desktop client registration + token rotation + heartbeat, SSE task
event stream, desktop accounts/tasks/content handlers, publish job endpoint,
and supporting repositories, services, sqlc queries, and migrations.

Hard cutover per plan: remove browser-extension monitoring callback endpoints,
stub legacy media API in admin-web, and delete monitoring_callback_handler.go.

apps/desktop-client/src/renderer/routes.ts

@@ -0,0 +1,19 @@
+import { createRouter, createWebHashHistory } from "vue-router";
+
+import AccountsView from "./views/AccountsView.vue";
+import AiPlatformsView from "./views/AiPlatformsView.vue";
+import DiagnosticsView from "./views/DiagnosticsView.vue";
+import HomeView from "./views/HomeView.vue";
+import TasksView from "./views/TasksView.vue";
+
+export const router = createRouter({
+  history: createWebHashHistory(),
+  routes: [
+    { path: "/", name: "home", component: HomeView },
+    { path: "/tasks", name: "tasks", component: TasksView },
+    { path: "/media-platforms", name: "media-platforms", component: AccountsView },
+    { path: "/ai-platforms", name: "ai-platforms", component: AiPlatformsView },
+    { path: "/accounts", redirect: "/media-platforms" },
+    { path: "/diagnostics", name: "diagnostics", component: DiagnosticsView },
+  ],
+});