MCP tools: read-only user management

[The127]

Summary

Add MCP tools for reading user data. These are safe read-only operations.

Depends on #232.

Tools

Tool	API Endpoint	Description
list_users	GET /{vs}/users	Paginated, searchable user list
get_user	GET /{vs}/users/{id}	User detail (id, username, displayName, email, emailVerified, isServiceUser)
get_user_metadata	GET /{vs}/users/{id}/metadata	Global + per-app metadata
list_passkeys	GET /{vs}/users/{id}/passkeys	WebAuthn passkeys for a user

Notes

• Never expose password hashes, TOTP secrets, or credential details
• Search/filter support for list_users (name, email)
• Pagination via page and pageSize parameters