[Feat][Audio] player: add clean-room MUCOM88 A-F playback

[Keitark]

Background / Goal

Add clean-room MUCOM88 support to the public RetroFM source tree without
copying or linking the CC BY-NC-SA MUCOM88 driver/compiler source. The first
complete target is the native A-F part set: FM1-3 and SSG1-3 on the existing
YM2203-compatible FPGA path.

Current behavior

The public source snapshot accepts MDX/PDX and YM2203 VGM/VGZ. A reviewed
private development branch contains an external-oracle importer and tests that
must be migrated without private music or generated conversions.

Expected behavior

• Parse CP932/ASCII .muc metadata and channel source with new GPL-compatible
  code.
• Sequence supported A-F commands into timestamped YM2203 register events.
• Preserve tempo, notes/rests, loops, key timing, voices, volume, pan, SSG
  mixer/noise/envelope, detune, and supported LFO semantics.
• Reject active G-K parts or unsupported commands before unmute.
• Keep official sample archives and generated personal imports outside Git.

Acceptance criteria

• No source is copied from the CC BY-NC-SA MUCOM88 implementation.
• Host tests cover malformed input, metadata, supported commands, loops,
  tempo, and register/timestamp traces.
• A rights-cleared A-F fixture plays through hardware JT03.
• Active G-K parts are rejected before playback.
• Existing MDX/PDX and VGM/VGZ tests remain green.
• Built, packaged, copied, booted, and audibly accepted states are reported
  separately.

Notes / logs / links

• Migrated from private development issue
  Keitark/EBAZ4205-RetroFM#1 as part of [Chore] repository: consolidate private development work #13.
• Official MUCOM88 programs, sample archives, music, and generated conversions
  are not public repository content.