Weekly meetups, host cities, and roll pages move to /meetup/

Added

• Weekly meetups: mark an event as weekly and it resets each rotation.
• Host city field with a searchable picker, and a playlist you can sort by city.
• A contextual sign-up banner on roll pages.

Changed

• Public roll URLs moved from /rolls/ to /meetup/.
• Hosts get a short roll form; the long one is admin-only.
• Free-tier host sign-up cap raised from 10 to 12.
• Submit form: neutral wording, Genres and Content Warnings side by side, a way to close an expanded field, and the Music field matched to the rest.

Fixed

• Dates shifting back by a day.
• Add to Calendar used the submission deadline instead of the show time.
• /watch/ showed the wrong film for one that had just been submitted.