feat(samples): seven more best-practices conversations from new sources

Adds conversations on a whole participatory budget cycle, groups keeping
their own clustering, screens between repeated rounds, asking who was
missing, switching on only what a project needs, quiet voices in a
teacher college and residents taking over hosting. Sharpens four
existing ones, and corrects nine that said hosts can upload text: the
dashboard upload takes audio only, so text goes in through the portal's
text option.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016MNLytqu8PVd9qtSMkP7dT

Author: claude