Update Auth0 plugin marketplace metadata (#3111)

Shorten the description to a concise tagline, add author.url for the
"Made by" link, and point homepage to auth0.com.

Plugin name stays lowercase to match marketplace convention.
Pinned source.sha left intact — maintained by bump-plugin-shas.yml.

Addresses #1736.

Co-authored-by: Bharath Natarajan <166125343+brth31@users.noreply.github.com>

.claude-plugin/marketplace.json

@@ -265,9 +265,10 @@
     },
     {
       "name": "auth0",
-      "description": "Add authentication to any app with Auth0. This plugin detects your framework, scaffolds the right Auth0 SDK integration, and guides you through login, logout, sessions, and protected routes — using current SDK patterns.",
+      "description": "Enterprise-grade auth, easy to implement. Add login, SSO, MFA, and access control to any app with framework-aware guidance.",
       "author": {
-        "name": "Auth0"
+        "name": "Auth0",
+        "url": "https://auth0.com"
       },
       "category": "security",
       "source": {
@@ -277,7 +278,7 @@
         "ref": "main",
         "sha": "838a181a235d8e563b437555794ddfe9bd60284b"
       },
-      "homepage": "https://auth0.com/docs/quickstart/agent-skills"
+      "homepage": "https://auth0.com"
     },
     {
       "name": "aws-agents",