Add a mock API with made-up data to look at the console

dev/mock-api.mjs answers the endpoints the screens call, with surrogate data, and keeps
what is changed in memory (zones, scopes, users, groups, rules, sessions, the cache).
`npm run mock` starts it on 127.0.0.1:5380, where the dev server's proxy already points.
.claude/launch.json starts the mock and the console together in the preview pane.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

package.json

@@ -8,6 +8,7 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
+    "mock": "node dev/mock-api.mjs",
     "build": "tsc -b && vite build",
     "lint": "oxlint",
     "lint:language": "node dev/check-language.mjs",