linx: extend v0.4 runtime and vector coverage

[zhoubot]

Summary

• extend Linx decode/translate/helper coverage for additional v0.4 scalar, FP, HL, and vector forms
• teach the virt loader to collect body ranges from ELF symbols for runtime execution support
• expand CPU state/debug plumbing used by the newer runtime paths

Validation

• ninja -C /Users/zhoubot/linx-isa/emulator/qemu/build qemu-system-linx64
• python3 /Users/zhoubot/linx-isa/tools/bringup/report_qemu_isa_coverage.py --spec /Users/zhoubot/linx-isa/isa/v0.3/linxisa-v0.3.json --qemu-meta /Users/zhoubot/linx-isa/emulator/qemu/target/linx/linx_opcode_meta_gen.h --report-out /tmp/qemu_isa_coverage_latest.json --out-md /tmp/qemu_isa_coverage_latest.md
• python3 /Users/zhoubot/linx-isa/tools/bringup/check_qemu_opcode_meta_sync.py --qemu-root /Users/zhoubot/linx-isa/emulator/qemu --allowlist /Users/zhoubot/linx-isa/docs/bringup/qemu_opcode_sync_allowlist.json --report-out /tmp/qemu_opcode_sync_latest.json --out-md /tmp/qemu_opcode_sync_latest.md

Notes

• the opcode-sync audit currently reports expected decode-only drift from newly added forms and will need the superproject allowlist/report update during repin

skill-evolve: no-update (module PR only; reusable qemu guidance already captured in linx-skills)