feat: add Admin API client, apps/chains commands, and config onboarding

Add AdminClient with full CRUD for apps, chains, and allowlists. All API
methods unwrap the { data: ... } envelope from the Alchemy Admin API.
Includes interactive app selection during access-key setup, new error
codes, and config support for app/access-key storage.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: CodesMcCabe

package.json

@@ -24,6 +24,7 @@
     "node": ">=18"
   },
   "dependencies": {
+    "@inquirer/prompts": "^8.3.0",
     "cli-table3": "^0.6.5",
     "commander": "^14.0.3",
     "yocto-spinner": "^1.1.0"