Simplify settings page and secure Twitch auth storage

[Jamesllllllllll]

Summary

Simplify the dashboard settings experience while adding the latest VIP token controls and securing Twitch OAuth tokens at rest.

What Changed

• Simplified the settings page layout and updated dashboard, playlist, bot, and overlay UI copy to expose VIP token duration thresholds, VIP request cooldowns, pick-order badges, and channel point eligibility more clearly.
• Added the supporting schema, migrations, server, worker, EventSub, viewer-request, and test coverage for VIP request cooldowns, duration thresholds, pick-order badges, and related playlist/request flows.
• Encrypted stored Twitch broadcaster and bot OAuth access/refresh tokens with AES-GCM, required TWITCH_TOKEN_ENCRYPTION_SECRET, and preserved compatibility by re-encrypting legacy rows on read.

How To Test

1. npm run format
2. npm run lint
3. npm run typecheck
4. npm run test
5. npm run check:staged
6. npm run check:prepush

Screenshots Or UI Notes

Settings, playlist, and overlay surfaces changed to support the new VIP token and pick-order controls. No screenshots are attached here.

Note: deployed environments now need TWITCH_TOKEN_ENCRYPTION_SECRET, and existing plaintext Twitch auth rows are migrated the next time they are read.

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-70.jameskeezer.workers.dev
Frontend worker: request-bot-pr-70
Backend worker: request-bot-backend-pr-70