Follow-me stair light for the Apollo MTR-1 and WLED

ESPHome package for the Apollo MTR-1: tracks people on the stairs with the
LD2450 radar and streams a lit window to a WLED controller over DDP. The
sensor serves a setup wizard that measures the stairs with one walk and
stores the setup on the device.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

wled/README.md

@@ -0,0 +1,40 @@
+# WLED
+
+## Settings follow-me needs
+
+Follow-me streams frames to the WLED controller over DDP (UDP port 4048)
+while a person is on the stairs. WLED's own state stays off; the stream lights
+the strip by itself, and the strip returns to WLED's own state after WLED's
+realtime timeout (2.5 s by default) once frames stop.
+
+The setup wizard's "Read" checks these settings and "Fix WLED settings" writes
+them.
+
+| Setting | Value | Why |
+|---|---|---|
+| Sync interfaces → Realtime → Receive UDP realtime | On | Turns on realtime input, DDP included |
+| Realtime → Use main segment only | Off | When on, realtime LED numbers become segment-relative and the wizard's LED marks shift |
+| Realtime → LED offset | 0 | Any offset shifts every LED |
+| Realtime → Force max brightness | On | The stream sets brightness; WLED's master brightness must not scale it again |
+| Realtime → Disable realtime gamma correction | On | The firmware applies its own gamma (2.2) |
+| LED preferences → Turn LEDs on after power up | Off (with "Pause While WLED On" set) | While WLED is on, follow-me pauses (manual control wins); a WLED that boots on would leave follow-me paused after every power cycle |
+| LED type / count | Set to match the strip | Follow-me reads both from WLED |
+
+Manual control: the firmware polls WLED's `/json/state`. With "Follow-Me Pause
+While WLED On" set (the default), while WLED reports itself on (turned on from Home Assistant, the WLED app or its button),
+follow-me sends nothing and makes WLED leave realtime mode at once.
+
+Tested with WLED 16 (RGBW strip).
+
+## Glow rules
+
+The firmware's glow follows rules found while tuning the look on a real strip:
+
+- No temporal dithering. At the lowest brightness steps the toggling is
+  visible as flicker.
+- No fading trail.
+- The glow shape reaches exactly zero at its edge. A Gaussian lingers at the
+  lowest steps, where each 8-bit step is visible.
+- Brightness comes only from the stream, not WLED's master brightness, to
+  avoid quantising twice.
+- Gamma 2.2 before quantising to 8 bits.