Explain non-database connectors in the ChatGPT plugin, mark directory sign-ups - #1545

Summary

Two follow-ups now that the AnythingMCP database plugin is published in OpenAI's plugin directory.

1. API connectors are explained in the plugin.
   • Problem: the plugin (/mcp/chatgpt-app) only queries databases. A workspace whose connectors are APIs (Odoo, Perplexity, Etsy…) saw them listed with nothing to do.
   • Change: anythingmcp_list_connectors now returns otherConnectorsHint. It names those connectors and says they are connected to ChatGPT from the dashboard (MCP Servers → server → ChatGPT).
   • Unchanged: the endpoint still never returns a server URL, by design since Add /mcp/chatgpt-app with fixed single-operation tools for the OpenAI plugin #1226. No tool name, description or schema changes, so the reviewed tool definitions stay the same.
2. Directory sign-ups are attributed.
   • Problem: someone who signs up from the directory plugin reaches /login through an OAuth redirect, so signup_attributed records direct.
   • Capture: the resource-indicator middleware captures the directory plugin endpoint (chatgpt-app, file-search) in a signed, httpOnly mcp_directory cookie, like the existing mcp_app one.
   • Marking: when an account created at most 2 h earlier authorizes that endpoint, signup_attributed gets directory: 'chatgpt' and directory_plugin, and a server-only directory_signup event is written once.
   • Unchanged: the channel fields are left untouched, because other code reads first_channel to mean "no stated intent" for direct.

Changes

• mcp-server/chatgpt-app-toolset.ts: OTHER_CONNECTORS_HINT, added to anythingmcp_list_connectors when non-database connectors are in scope.
• auth/resource-indicator.middleware.ts: DIRECTORY_PLUGIN_ENDPOINTS, MCP_DIRECTORY_COOKIE, parseDirectoryPlugin.
• audit/directory-signup.ts (new): markDirectorySignup, which never throws.
• auth/login.controller.ts: calls it when an authorize flow reaches the grant step.
• audit/product-event.service.ts: directory_signup, server-only.
• Docs: docs/integrations/chatgpt.md and docs/operations/signup-attribution.md (with a report query).

Cloud and self-hosted: same code in both. The directory plugins exist only on Cloud, so on self-hosted the cookie is simply never set.

Type

• New feature

Testing

• Added/updated unit tests
  • chatgpt-app-toolset.spec.ts: the hint appears with API connectors, is absent for databases only, and no /mcp/ URL appears.
  • directory-signup.spec.ts: inside and outside the window, repeat, missing row, DB failure, parseDirectoryPlugin cases.
  • resource-indicator.middleware.spec.ts: cookie set for chatgpt-app, cleared for /mcp.

Commands, run in packages/backend:

• npx jest src/audit/directory-signup.spec.ts src/auth/resource-indicator src/auth/login.controller src/mcp-server/chatgpt-app src/audit/product-event: all passing.
• npx eslint <changed files>: clean.
• npx tsc --noEmit -p tsconfig.json: clean.

Checklist

• My code follows the existing code style
• I have tested my changes locally
• I have updated documentation (if applicable)
• This PR has a descriptive title