PTOAS: align with PTO ISA 0.58.3

[zhoubot]

Closes #7

Summary

• lock exact PTO-SPEC v0.58.3 identity and the 109-operation PTOAS contract snapshot
• support independent zero/A-only/B-only/two-scale schemas for TMATMUL/TGEMV MX base/ACC/BIAS
• require E8M0 scales only for compact FP8/FP4 inputs and reject missing/extra/wrong-side scales
• preserve optional operand segments through PTO-BC encode/decode
• emit exact final TileOP operand order and real Linx frontend type spellings
• close real target syntax, object, link, and PTO ELF identity gates without shims, stubs, or waivers

Exact authority

• PTO-SPEC tag: v0.58.3
• source commit/tree: e599a3d36ebfad43362ff591ea5e128816c684c7 / abb6899d2e664e378ac9c1b77062670daa4d31b4
• encoding ABI: pto-isa-0.58.3-mode-function-v1
• projection SHA-256: 8a48b80e04484c70870f155bf9efc79d2a805cf99e809f4e4e8a7e6a7eb34172
• content SHA-256: f299fe3d256c5d071e57bb4aaa2be2de2e4a386ae090048df1f73ae92d392678
• merged LLVM commit/tree: b7c83f68bf84125e696a70bec4b665c70a3b584d / c11bd80c7dd34ed4438de1da6bde0a01eae8c76d
• final TileOP commit/tree: bd1ecca97ca47da0edc462c1ce19749c6940780e / 854c463c21f9b758186b718105f4b035019cdd30

Verification

• PTOAS/PTO-BC build: PASS
• exact PTO lock/source and release pin checkers: PASS
• lit: 240/240 PASS
• CTest: 26/26 PASS
• checker/release units: 20/20 PASS
• PTO-BC four scale schemas: PASS
• 24 generated TMATMUL/TGEMV MX calls: Linx syntax and target objects PASS
• final TileOP frontend IR/object/disassembly gate: PASS
• literal phase-C sysroot link smoke: 3/3 PASS
• exact PTO 0.58.3 ELF identity validation: 3/3 PASS
• no shadow template_asm.hpp, host shim, stub API, or waiver

Delivery state

Draft only. No merge or release is performed by this PR.