Chatbot survey

[MJoaaquin]

Summary

This PR adds per-map bot configuration. The bot is off by default: it sends nothing
until the map owner configures it and enables it for a live device.

With the bot enabled, when content arrives from a new mapper the bot guides them: it asks
for a photo/video/audio, asks for the location, and — if the owner configured them — runs a
survey of single-choice and free-text questions. Answers are stored per point
and shown in the map popup. After several invalid replies in a row, the bot offers to
cancel or restart the mapping.

How the bot gets enabled

• Off by default. maps.bot_active starts as false. While it is false, the
  listener does not even pick up that device's messages for the bot: only devices whose
  live map has bot_active = true are processed.
• The owner configures the messages and questions from a new page (Bot setup,
  /bot-setup/:id), reached via the robot button on each live map in the list. Non-live
  maps have no bot.
• A toggle enables the bot for that map. It cannot be enabled with an incomplete
  configuration: the PUT checks that every message the bot needs is present and returns
  422 if any is missing. A partial configuration can still be saved with the bot off.
• The bot runs for a device only if its live map has bot_active = true and a complete
  configuration. Otherwise the message passes straight through to the pairing pipeline.
• Unlinking the map (PUT /map/{id}/unlink/) turns off bot_active along with is_live.