feat(Host): add a 下一首 button beside 收卷並計分

[xinshoutw]

Summary

• Adds a 下一首 button to the /host view, taking the right third of 收卷並計分's half (styled like the dashboard's 下一首)
• It unlocks only after the selected song is closed and locks again once the next song is selected, until that song is closed too; it stays locked on the last song
• The lock is derived from the server state (round.songId === songId and closed), so it survives reloads and switching between the dashboard and host views
• On phones (≤759px) the button shrinks to its icon, so the row fits a 320px screen

Test plan

• Headless Chromium against wrangler dev: open → close → next → open → close → next → close on the last song, checking each button's disabled state
• Screenshots at 1280, 768, 375 and 320px; no horizontal overflow
• npm test

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 73e8820a-d4eb-46c9-b9e4-9e99b1fad0c7

• Autopilot · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Autopilot is currently an internal CodeRabbit preview.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}