Call recorder: let a user send the recording bot to a meeting now

Scope & Context A Call Recorder bot joins CALL_RECORDER_JOIN_EARLY_MINUTES before the meeting starts. That is one workspace-wide setting, read whenever a bot is scheduled or rescheduled. When a single meeting starts early, for example when the organizer asks people to join 15 minutes before the invite, there is no way to get the bot into that meeting only: • Changing the setting moves every upcoming bot on the next reconciliation, not just this one. • Switching Recording Bot Off and On cancels the bot, and the re-request waits for the nightly recovery run (#26808), so the bot arrives late instead of early. Current behavior There is no per-meeting control over when the bot joins. Expected behavior A command menu item on a calendar event and on its call recording, "Send recorder now": • If the meeting has a scheduled bot that has not joined, move its join_at to now with Recall's update-bot call, the one rescheduleRecallBot already makes. ̶…