[Feature]: MateChat Mention Trigger (Quick Commands)

[Raven-Book]

Related links

https://matechat.gitcode.com/components/mention/demo.html

Task List

• Mention
• Mention Menu

[moeyue23]

If this issue hasn’t been assigned yet, may I kindly take it on?

[fu050409]

@moeyue23 Of course, contributions are very welcome!