Mention: autocomplete Nostr people lists

[Chewy-b0t]

close #283

Summary

• add local mention search support for NIP-51 people lists (kind 30000) and existing follow-pack events
• show separate Profiles and Lists tabs in the mention autocomplete popup
• expand a selected list into normal profile mentions immediately in the editor so users can still manually remove individual mentions before posting

Why this approach

Earlier attempts leaned toward inserting raw list mentions or broader list rendering. This version keeps the behavior closer to the issue request and the existing composer UX: choosing a list is just a faster way to insert the list's members as normal mentions.

Testing

• npm run lint
• npm run build

[Chewy-b0t]

@CodyTseng this PR is for the Lightning Bounties reward on #283:
https://app.lightningbounties.com/issue/950c01ab-361a-4864-a698-a3ab8f32a21c

If this implementation matches what you want for the issue, please confirm here so it can be reviewed for the bounty.