Add Daylight Cycle value source type

New value source that outputs brightness (0-1) based on the daylight
color LUT, computing BT.601 luminance from the simulated sky color.
Supports real-time wall-clock mode or configurable simulation speed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

TODO.md

@@ -51,6 +51,6 @@ Priority: `P1` quick win · `P2` moderate · `P3` large effort
 
 - [ ] `P1` **Collapse dashboard running target stats** — Show only FPS chart by default; uptime, errors, and pipeline timings in an expandable section collapsed by default
 - [ ] `P1` **Review new CSS types (Daylight & Candlelight)** — End-to-end review: create via UI, assign to targets, verify LED rendering, check edge cases (0 candles, extreme latitude, real-time toggle)
-- [ ] `P1` **Daylight brightness value source** — New value source type that reports a 0–255 brightness level based on daylight cycle time (real-time or simulated), reusing the daylight LUT logic
+- [x] `P1` **Daylight brightness value source** — New value source type that reports a 0–255 brightness level based on daylight cycle time (real-time or simulated), reusing the daylight LUT logic
 - [ ] `P1` **Tags input: move under name, remove hint/title** — Move the tags chip input directly below the name field in all entity editor modals; remove the hint toggle and section title for a cleaner layout
 - [ ] `P1` **IconSelect grid overflow & scroll jump** — Expandable icon grid sometimes renders outside the visible viewport; opening it causes the modal/page to jump scroll