[Feature] Estimating Lunar Illuminance

### Short summary Sensor which indicates how much moonlight there is ### Detailed description _This is a preliminary idea—please consider it a starting point and open for discussion._ Expose an estimated moonlight illuminance (in lux) based on the current Moon Illumination Fraction, altitude, and distance Somewhat like [sunlight illuminance](https://github.com/pnbruckner/ha-illuminance) **Why is this feature valuable? Who benefits?** - Astronomy enthusiasts can automate telescope dome lighting based on actual moonlight. - Outdoor photographers can adjust camera settings or lighting scenes automatically on bright or dark nights. - Home automation users can dim or brighten outdoor lights relative to natural moonlight, An empirical formula could be: Moonlight Illuminance = `E ≈ 𝐸0 ⋅ 𝑓 ⋅ cos(z) ⋅ (𝐷avg/𝐷)²` Where: 𝐸0 ≈0.25lux — approx. illuminance of full moon at zenith (User can override E0 for site calibration?) 𝑓 = Illumination fraction z = zenith angle = 90° − altitude cos(z) = projection factor for how high the moon is in the sky D = current Moon distance Davg = average Moon distance (≈ 384,400 km) ### Examples 🖼️ _No response_ ### Additional context 🗒️ [Krisciunas & Schaefer 1991 empirical model](https://iopscience.iop.org/article/10.1086/132921) [[moonlit](moonlit: R package to estimate moonlight intensity)](https://github.com/msmielak/moonlit)