Improve mobile playlist and search UX

[Jamesllllllllll]

Summary

Continue issue #27 with mobile-focused home page and public playlist/search polish, plus blacklist-aware request behavior.

Closes #27.

What Changed

• Added homepage padding and moved the primary actions into the Find a song and Manage your channel cards.
• Improved search result layout on smaller screens so metadata stays left and request actions plus charter/updated metadata stack cleanly on the right.
• Updated search result summaries to report visible counts and use Found X songs wording.
• Hid blacklisted songs by default on public playlist pages, moved the toggle into the existing search filters panel, and marked shown blacklisted search results as blocked and non-interactive.
• Removed charter rows from the blacklist summary panel while still indicating creator/charter blacklist reasons on playlist/search rows.
• Standardized chat rejection replies for blacklisted requests, including direct song:<id> requests.
• Updated eventsub tests for the new blacklist reply copy.

How To Test

1. Open / on desktop and mobile widths and verify the hero has top/side padding and the card actions live in the card header rows.
2. Open /search and verify the summary badge says Found X songs and the mobile result layout keeps song metadata on the left with request actions on the right.
3. Open a public playlist page with blacklist data and verify blacklisted queue items are hidden by default.
4. In Search to add a song, open Show filters, toggle Show blacklisted songs, and verify blacklisted matches appear with blocked styling, blacklist messaging, and disabled request buttons.
5. Request a blacklisted song in chat using either a search term or !sr song:12345 and verify the reply says it cannot add the song.

Screenshots Or UI Notes

Visible UI changes affect the home page, public playlist pages, and search results at mobile sizes. No screenshots attached.

Checklist

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

Known limitation: local npm run lint on this Windows checkout still reports pre-existing Biome formatting/line-ending issues in untouched files outside this PR. The branch-local checks I ran were npm run typecheck, npm run test, and npm run build.

[github-actions]

Preview deployment updated.

App: https://request-bot-pr-31.jameskeezer.workers.dev
Frontend worker: request-bot-pr-31
Backend worker: request-bot-backend-pr-31