Reverts the previous merge: "leds" now only ever parses on/off (a pure
word command again, no numeric fallback), and brightness moves to its
own "leds.brightness <0-100>" command instead of overloading "leds"
with a value that could be either a word or a number. Checked before
"leds " in the chain since it shares the same 4-byte prefix. Still
RAM-only, no savePrefs() call in the brightness branch.
This is the syntax settled on after comparing two options: reuse
"leds" via a namespaced brightness command (chosen), vs a full
per-LED led.hb/led.tx split like the RAK3401 branch (not chosen,
decided to apply the "leds"/"leds.brightness" shape everywhere without
exception, including any future RAK3401 rework).
ZephCore T096
1b7f167479