GH.10 Assistant/MCP: tools to place electrical devices (sockets, switches, lights, …)

### What do you need to do

Let an AI assistant place electrical devices (sockets, switches, luminaires, detectors, boards, …) through the MCP / assistant interface, the same way it can already draw walls, openings, floors and cable carriers.

Today the assistant tool set has no way to create a device:

- `carrier_add` draws cable trays and conduits, and `carriers_check` / `lighting_check` / `loads_set` / `photometry_set` work on what is there,
- but none of the ~80 tools (`agents.js`, `mep-agents.js`, `bim-agent.js`, …) places a device. `furniture_add` only furnishes rooms by rule.

So an assistant can route conduits to an outlet it cannot create, and an electrical plan still has to be clicked in by hand.

The building blocks already exist in `app/res-elec.js` (`placeDevice`, `changeDevice`, `linkLight`, `removeDevices`, `DEVICES` with 33 kinds). Exposing them as tools would cover it, for example:

| Tool | Does | Arguments (sketch) |
|---|---|---|
| `devices_add` | Place one or more devices | `level`, `kind` (a key of `DEVICES`), `at` [x, y] mm, optional `wall` (snap to the nearest wall face like the UI does), `height`, `angle`, `circuit`, `load_w`, `tag` |
| `device_change` | Change tag, circuit, load, height, position | `guid` + fields |
| `lights_link` | Link a switch / sensor to the lights it controls | `switch`, `lights[]` |
| `devices_delete` | Remove devices (and unlink lights) | `guids[]` |
| `devices_list` | Devices of a level with kind, tag, circuit, load, height, host wall, linked lights | `level` |

Typical requests this would enable:

- "Put a double socket every 2 m along the walls of the living room on level 1, 300 mm high, circuit 3."
- "Add a ceiling li…

Opened on GitHub by a Discord member: https://github.com/getcadcraft/bimcraft/issues/16

Sweep 2026-11-05: accepted into 0.9. Assistants/MCP tools to place electrical devices; belongs with the add-on's device kinds (ELEC-BUILDING).

bim-hosts-09 2026-11-06 (done): see docs/0.9-sessions/bim-hosts-09.md.