List the caller's MCP connectors

Returns the MCP connectors the authenticated tenant may reach, with their health status. Deployment-shared connectors (those registered under the wildcard tenancy *) are included for every tenant; another tenant's connectors are not (platform/agent/mcp_handler.go:612-620).

Connectors provide access to external data sources:

• PostgreSQL
• Cassandra
• Salesforce
• Snowflake
• Amadeus (travel API)
• Slack

Authentication. Wrapped in apiAuthMiddleware (platform/agent/mcp_handler.go:581); the tenancy comes from the credential, never from a caller-supplied header or path segment. Registered for GET only — apiAuthMiddleware forwards CORS preflights unauthenticated, so registering OPTIONS would reach the handler with no identity in context.

(Behaviour change in #3067: this route was previously registered with no auth middleware and returned every tenant's connector names, types, versions, capabilities, health and raw driver error strings to an anonymous caller.)