LinxISA v0.58.0

LinxISA v0.58.0 aligns its scalar, block, and tile surfaces with PTO ISA 0.58.0 while retaining the Linx-only two-level vector extension.

The release is a hard break. It publishes 474 PTO scalar forms, 99 PTO command forms, 109 PTO tile operations, six PTO-reserved Linx vector encodings, and the absolute-index core-private S0..S255 Shared tile register bank.

The retained PTO memory forms include BSTART.MGATHER.MASK, BSTART.MSCATTER.MASK, and BSTART.MGATHER.CAS; their direct tile operations are MGATHER_MASK, MSCATTER_MASK, and MGATHER_CAS.

All generated codecs, Sail decode, field definitions, release projections, and CI entry points now target isa/v0.58/linxisa-v0.58.json.