fix: pin kiosk keyboard to viewport bottom for more search results

[thewrz]

Summary

• Pin the virtual keyboard to the bottom of the viewport using position: fixed instead of inline flow inside the modal
• Add padding-bottom: 280px to the keyboard-active modal to prevent content from being hidden behind the fixed keyboard
• Increase compact search results max-height from 120px to 50vh so 5-6+ results are visible above the keyboard

Context

On the kiosk touchscreen, only ~2 search results were visible because the inline keyboard consumed most of the modal's vertical space. By fixing the keyboard to the viewport bottom and letting the search results expand, guests can now see many more results without scrolling.

Test plan

• Desktop browser: open /e/{code}/display → "Request a Song" → no virtual keyboard, search results display normally
• Touch simulation (DevTools): keyboard pins to bottom of viewport, search results fill space above it
• Pi kiosk: 5-6+ search results visible above the keyboard
• Keyboard taps still work (still a DOM child of modal, events propagate correctly)
• Modal close (X, overlay click) still works with fixed keyboard