Add charter blacklisting

[Jamesllllllllll]

Summary

Adds charter blacklisting with exact charter-ID matching so channels can block songs by specific charters across moderation, chat requests, and public playlist UI.

Resolves #5.

What Changed

• Added a new blacklisted_charters table and migration so charter blacklist entries are stored by exact charter ID.
• Added moderation search for charter names using the catalog author_id / creator_name data, with add/remove support in the dashboard moderation page.
• Extended request validation so blacklisted charters reject matching chat requests by exact charter ID and return a charter-specific Twitch reply.
• Surfaced blacklisted charters anywhere blacklist entries are shown in the public playlist and manage-playlist views.
• Updated blacklist/help messaging and tests to cover charter blacklist behavior.

How To Test

1. Run npm run lint
2. Run npm run typecheck
3. Run npm test
4. Run npm run build
5. Open dashboard moderation, search for a charter by name, and add them to the blacklist.
6. Confirm the charter appears in moderation, public playlist, and manage-playlist blacklist UI.
7. Request a song charted by that blacklisted charter in Twitch chat and verify the request is rejected with the charter blacklist message.

Screenshots Or UI Notes

• Moderation now includes a Blacklisted charters section alongside artists and songs.
• Public and dashboard blacklist panels now show artist, charter, and song blacklist entries together.

Checklist

• I tested the change locally
• I updated docs or examples if needed
• I called out any follow-up work or known limitations

[github-actions]

Preview deployment updated.

App: https://request-bot-pr-29.jameskeezer.workers.dev
Frontend worker: request-bot-pr-29
Backend worker: request-bot-backend-pr-29