Add Logitech ASTRO A50 Gen 5 (046d:0b1c)

[lluiseduardo-silva]

Changes made

Adds support for the Logitech ASTRO A50 Gen 5 base station (USB 046d:0b1c).

The base station uses a vendor-specific HID protocol (report ID 0x02 on usage page 0xff32,
interface 8) — not HID++ and not the Centurion / report-0x51 protocol used by the A50 X.
It was reverse-engineered from USB captures.

Capabilities (all verified on real hardware):

• Battery status (CMD 0x06)
• Chatmix (CMD 0x0a)
• Sidetone (CMD 0x09)
• Lights / dock LED (CMD 0x0f)
• Parametric equalizer (CMD 0x0d) — 10 bands, gain ±6 dB, Q 0.031–7.969
• Microphone noise filter (CMD 0x14) — the A50 has 4 levels; HeadsetControl's 0/1/2
  (off/low/high) maps to A50 Off / Night / Tournament

New header-only device lib/devices/logitech_astro_a50.hpp, registered in
lib/device_registry.cpp, README device table updated. clang-format-18 clean, unit tests pass.

The A50 exposes further controls (master volume, mic EQ, broadcast/stream mix, device state) that
don't map to any existing HeadsetControl capability — documented in
docs/ASTRO_A50_EXTRA_FEATURES.md and intentionally left out of this PR (they'd need new core
capabilities; happy to contribute upstream if you're open to it). A companion GUI
(https://github.com/lluiseduardo-silva/HeadsetControlA50Gui) implements them meanwhile.

docs/ASTRO_A50_EXTRA_FEATURES.md and intentionally left out of this PR (they'd need new core
capabilities; happy to contribute upstream if you're open to it). A companion GUI
(https://github.com/lluiseduardo-silva/HeadsetControlA50Gui) implements them meanwhile.

Checklist

• I adjusted the README (if needed)
• For new features in HeadsetControl: discussed beforehand — N/A, this adds a device using
  existing capabilities, not a new app feature.

Tested on hardware

$ headsetcontrol -b -m
Found 1 supported device(s):
Logitech ASTRO A50 Gen 5 (A50) [0x046d:0x0b1c]
Battery:
Status: BATTERY_AVAILABLE
Level: 87%
Chatmix: 54

Lights, sidetone and parametric EQ also verified directly on the device
(a ±6 dB bass boost/cut via --parametric-equalizer was clearly audible).

[stoffer123]

Update: working on A50 Gen 5 (046d:0b1c, bcdDevice 1.03) after a power-cycle 🎉

Both battery and chatmix now return correctly, no sudo needed:

$ headsetcontrol -m
 Logitech ASTRO A50 Gen 5 (A50) [0x046d:0x0b1c]
Chatmix: 64
(value tracks the physical dial as expected)

$ headsetcontrol -b
-> returns battery level fine

Earlier I had persistent "Operation timed out" on every HID query (even as root,
even with the headset awake and playing audio). What fixed it was fully power-
cycling the base station (pulling the power, not just USB), then replug. So it
was a stuck device state, not a protocol/variant issue — for the record, this is
NOT the report-0x51 "A50 X" variant: my HID control interface is interface 8,
exactly where the PR expects it.

One packaging nit: cmake --install writes the udev rules to
/usr/local/lib/udev/rules.d/, which udev doesn't scan by default. I had to copy
70-headsets.rules to /etc/udev/rules.d/ for non-root access to work. Might be
worth a README note or installing to /etc directly.

Thanks for the work on this — verified on CachyOS (Arch), build is solid.