IP Access Control: support address groups for labeled allowlist management

Currently, IP Access Control is a flat list of individual IP addresses and descriptions. This can become difficult to manage when users need to allowlist a large number of related IP ranges, such as OpenAI's ChatGPT connector CIDRs for MCP.

While descriptions can help identify what each entry is for, there is currently no way to group related addresses together. This makes larger allowlists harder to organize and increases the chance of missing or incorrectly updating an address when changes are needed.

It would be helpful if admins could organize allowlist entries into named groups, such as "Office," "VPN," or "OpenAI - ChatGPT / MCP." This would make IP Access Control much easier to organize, review, and maintain.