Feature request: MCP should support tagging/mentioning other issues (clickable links to other Plane objects)

Problem

When using the Plane MCP to write/update issue descriptions or comments, I cannot tag or mention another Plane object (e.g., another issue). As a workaround I currently copy-paste the raw page ID into the text, which is not useful as a reference.

Suggested solution

Ideally I'd like to tag other Plane objects (issues, cycles, pages, etc.) and have them rendered as clickable links that redirect to the referenced object.

This could work like:

1. Support mention syntax (e.g., @issue/PLAN-123) in content created via MCP, similar to the web UI's mention/tag feature.
2. When the tagged text is rendered, it becomes a clickable link that navigates to the referenced Plane object.

Additional context

• This would make cross-references between issues much more readable than a raw page ID.
• It should ideally work the same way as the existing mention feature in the Plane web UI.

Start at the Plane MCP entry point that creates or updates issue descriptions and comments, then trace the web UI's existing mention/tag handling and rendering. Confirm how issue, cycle, and page references are represented and define completion as MCP-created references rendering as clickable links to the corresponding Plane objects.