Flotilla Chat

* Replace the home page with a dashboard of unread conversations, space activity and a network feed * Redesign the calendar with month, week and agenda views, and add RSVPs * Redesign classifieds as a browsable marketplace * Rework threads as one continuous list with unread indicators on every board * Add slash commands * Add read out loud and voice dictation * Add relay data import and export to the hosting panel * Add a mute setting for rooms * Rework search dialogs * Improve link previews, falling back to an inline link when one fails * Persist direct messages so history survives relay retention * Add an image by upload or url from one dialog, and play audio attachments inline * Let space icons be dragged to reorder in the sidebar * Open the space menu in a drawer instead of navigating away from the room * Fix push notification delivery, taps and badge counts * Performance improvements to feeds, room chat and reactions