fix: reject out-of-range led brightness instead of silently clamping

led accepted any u16 and main.rs clamped to 0..=1000 with no feedback,
inconsistent with sidetone which rejects out-of-range at parse time.
Add a clap range validator (0..=1000) and drop the silent clamp, so
invalid input now fails loudly.

Further quality-audit follow-ups:
- remove dead BragiDevice::open() (no caller; binary uses open_with_verbose)
- add tests: led range validation, format_battery for all status
  variants, waybar "unknown" class

Bump 0.1.2 -> 0.1.3.

Cargo.lock

@@ -144,7 +144,7 @@ checksum = "1d07550c9036bf2ae0c684c4297d503f838287c83c53686d05370d0e139ae570"
 
 [[package]]
 name = "corsairctl"
-version = "0.1.2"
+version = "0.1.3"
 dependencies = [
  "alsa",
  "clap",