[Lane 2 · kotlin-core] GGUF IQ dequant — MXFP4 dequantization #1410

Sub-issue of #1408 ([Feature]: GGUF dequantization for the IQ1/IQ2/IQ3 families and MXFP4).

Lane: 2 · Kotlin core
Skill needed: Kotlin; bit manipulation.
Size: s (a few hours)
Blocked by: #1409

What to do

1. Add MXFP4 to DequantOps.kt following the IQ4_NL implementation in the same file.
2. Test against the Lane-1 reference data in skainet-io/skainet-io-gguf/src/commonTest; run ./gradlew :skainet-io:skainet-io-gguf:jvmTest.

Acceptance

• Bit-identical to the reference
• Result reported back on the parent issue

Notes

If something here turns out to be wrong or much bigger than the size label, comment on this issue or open a specific bug instead of blocking the parent.

Coverage matrix: docs/modules/ROOT/pages/reference/ops-status-matrix.adoc · How lanes work: Issue taxonomy