What changed

No user-facing behavior change. Internal documentation update: comments in AAP protocol code now describe message type 0x0054 ("Set Band Edges") as configuring the AirPods radio's allowed RF bands — not the EQ-related guess that was inherited from the earlier "Personal Mixing Engine" reading of the neighbouring 0x0053 message.

Technical Context

• Affirmative source: a PR Device: Revise AAP protocol notes on hearing-aid message #544 follow-up comment from an external contributor pointed out that 0x0054 gates radio frequency bands. AirPods Pro 2 USB-C and newer can transmit on 5 GHz / 6 GHz U-NII bands in addition to 2.4 GHz ISM — Apple uses this for the proprietary lossless audio mode with Apple Vision Pro.
• The "type" field is a band code from Apple's BSM_BAND_CODE_* enum (identified via FCC firmware analysis): 0x0 = ISM24, 0x1 = U-NII-1, 0x2 = U-NII-3, 0x3 = U-NII-4, 0x4–0x7 = U-NII-5A/B/C/D, 0x8 = INVALID.
• Scope is deliberately comments-only — no new AapCommand.SetBandEdges(...) subclass, no payload decoder. CAPod still observes-but-does-not-decode this opcode; adding structure now would be premature without sample captures.
• The inline comment in AapSessionEngine no longer carries the "neighbouring opcode" framing, since the kdoc on AapMessageType now carries the full story.

Refs #544.