The G522 exposes AdvancedParaEQ (0x020D), a different EQ feature than
the PRO X 2's OnboardEQ (0x0636). Key differences:
- 3-byte-per-band wire format ([freq_hi, freq_lo, gain]) vs 0x0636's
4-byte-per-band ([freq_hi, freq_lo, gain, Q])
- Device handles biquad coefficient computation — no host-side DSP math
- Has explicit direction (playback/capture), multiple preset slots with
getActiveEQ/setActiveEQ for switching, preset friendly names
Adds new advanced_para_eq.py module with getInfos, getActiveEQ, and
getCustomEQ helpers (function 0, 3, 1 respectively). Re-exported from
hidpp20.py following the onboard_eq.py pattern.
HeadsetAdvancedEQ setting displays the currently-active playback EQ
using the same RangeFieldSetting + PackedRangeValidator UI pattern as
HeadsetOnboardEQ, so the graphic EQ widget looks the same.
**Writes are intentionally disabled for now** — prepare_write returns
None and write() logs "read-only mode" without sending anything. This
lets us verify the wire format matches the protocol doc against real
hardware before risking a write that could misconfigure the DSP. Once
read output is confirmed sensible, we'll wire up setCustomEQ (function
2) to enable writes.