Auto-switch Gently UI to dark mode when room light is turned off (SwitchBot)

[pskeshu]

Suggestion from Magdalena

When we turn the room light off using the SwitchBot switch, the Gently UI should automatically switch to dark mode (and switch back to light mode when the light is turned on).

Idea

• Hook into the SwitchBot state (room light on/off).
• When the light is turned off, switch the Gently web UI to dark mode.
• When the light is turned on, switch back to light mode.

This makes the UI more comfortable to view in a darkened imaging room, where the lights are often switched off during acquisition.

Notes / open questions

• How do we read the SwitchBot state (API / webhook / polling)?
• Should this be automatic by default, or an opt-in setting?
• Should it respect a manual override if the user has explicitly chosen a theme?

Reported by Magdalena.