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.

packages/ui-shared/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "@geo/ui-shared",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "exports": {
+    ".": "./src/index.ts",
+    "./tokens": "./src/tokens/index.ts",
+    "./tokens.css": "./src/tokens/index.css",
+    "./composables": "./src/composables/index.ts",
+    "./components": "./src/components/index.ts"
+  },
+  "peerDependencies": {
+    "ant-design-vue": "^4.2.6",
+    "vue": "^3.5.31"
+  }
+}