linxisa: refresh final PTO 0.58.3 authority

[zhoubot]

Summary

• authenticate the final LinxISA 0.58.3 catalog bytes at 1926864fed9405761f783b130674c45f92210d3d
• pin system/sanitizer CI and model documentation to that immutable authority
• add explicit positive and hostile freshness coverage for the corrected HL.LUI high-half materialization and CSEL SrcRType=10 .neg conventions
• preserve the exact PTO 0.58.3 lock, manifest, release identity, and 757/2643/3375/792 codec cardinalities

The supported generator was run with an explicit authority root. It regenerated 757 forms, 2643 fields, 3375 pieces, and 792 constraints; the committed generated header/source remained byte-for-byte unchanged because the authority correction changes semantic conventions, not instruction encodings.

Verification

• python3 tools/isa/gen_minst_codec.py --authority-root <linx-isa> ... --check — PASS
• LINXISA_AUTHORITY_ROOT=<linx-isa> python3 tests/checks/test_gen_minst_codec.py -v — 14/14 PASS
• Debug CMake + Ninja build — PASS
• cmake --build <debug> --target check-isa-codec — PASS
• full ctest --test-dir <debug> --output-on-failure — 12/12 PASS
• Release CMake + Ninja build — PASS
• ./tools/ci/run_clang_format_check.sh — PASS
• markdownlint-cli2 README.md 'docs/**/*.md' — PASS
• repository clang-tidy script with matching Homebrew LLVM build database — PASS (pre-existing warnings only, no errors)
• git diff --check — PASS

Closes #14