linx: reject PTO 0.58.5 retired TEPL selectors

[zhoubot]

Closes #78.

Summary

• removes six retired TEPL forms from decodetree, translation, and opcode metadata
• removes their architectural selector mappings while leaving unreachable private helpers untouched
• documents the former selector values as reserved
• adds a regression preventing decode or reachability from returning

Verification

• retired-selector source regression: 3/3 passed
• existing PTO 0.58.3 contract: 14/14 passed
• existing decode metadata tests: 8/8 passed
• clean linx64-softmmu build: passed
• superproject opcode metadata audit: passed

Integration chain

• feat: unify ASLRef functional-model architecture boundary PTO-ISA/pto-spec#188
• feat: add ASLRef-backed PTO reference model PTO-ISA/asl-model#2
• LinxISA/SuperScalarModel#428
• isa: regenerate codec for PTO 0.58.5 linx-model#19
• bringup: pin PTO ASLRef functional-model chain linx-isa#191

Draft only; do not merge before the producer chain is accepted.

[zhoubot]

Integration chain: PTO-ISA/pto-spec#188 -> PTO-ISA/asl-model#2 -> LinxISA/SuperScalarModel#428 -> LinxISA/linx-model#19 -> LinxISA/linx-isa#191. The superproject TEPL selector gate passes with this exact QEMU commit; this remains a Draft and must not be merged independently of the chain.

[zhoubot]

Superseded by merged PR #80, which includes this retired-selector cleanup in the complete PTO 0.58.6 QEMU update.