feat: room devices — see what's connected and hand the speaker around

[madeofpendletonwool]

Why

Only the device itself could become a room's speaker. Once a Syncphony box stopped being the speaker, the only way back was to pick up the TV remote and press "Play the audio here".

What

• Devices list (GET /rooms/{id}/devices). Shows the room's paired screens, then every signed-in browser with the room open. Browsers report kind (computer/phone) and name on the room socket. A browser that doesn't report a kind is listed as a phone. Everything is kept in memory, so there's no migration. A new devices.updated event fires when a browser opens or closes the room.
• Make speaker (PUT /rooms/{id}/devices/{deviceId}/speaker). Sends device.command {action: speak} to that one device, which then claims the room itself through the usual PUT /player. A box starts playing on its own. Other screens and computers show the existing tap/OK button if their browser blocks autoplay.
  • Screens: whoever may manage them, with audio on, while online.
  • Browsers: only your own, and never a phone (device_is_phone).
• Stop (DELETE …/speaker). Sends stop first, then releases the device. The device goes quiet before it sees the room without a speaker, so it doesn't claim the room straight back, which is what used to happen after a remote release.
• UI
  • A Devices sheet, opened from the room menu and from "Devices in the room" under the speaker panel. It offers Make speaker, Stop, and "Play here" for this browser.
  • The Big screen dialog's Screens list gets "Make it the speaker" / "Stop the speaker" for screens with audio.
• ADR 0019 documents the design.

Tests

• Go:
  • devices_test.go covers the list and its per-viewer permissions, joining and leaving, the make-speaker rules, and that the stop command reaches the device before the release.
  • Full go test -race ./... passes, and golangci-lint is clean.
• Web:
  • devices.test.ts covers device kind detection, row details, and command handler order. Two new tv-audio tests cover a remote speak and a remote stop.
  • All 316 tests pass, and typecheck and lint are clean.

Not tried yet in a real browser or on a box.