Add ARM32 EABI5 packing and harden loader checks

[hansxia]

Summary

• Add ARM32/EABI5 ELF32 packing, loader, stubgen, and x86_64 WSL host tooling.
• Keep packed executables persistent by default and preserve argv[0] for service compatibility.
• Validate packed sizes with bounded arithmetic and reject oversized inputs before allocation.
• Propagate OpenSSL transform failures instead of continuing with a partial buffer.
• Add bilingual handoff/change documentation and ARM64/ARM32 regression guards.

Validation

• make clean all verify-build test all32 verify-build32 test32 passes in x86_64 WSL.
• 2 GiB+1 sparse input is rejected without creating an output file.
• ARM64 and ARM32/EABI5 build artifacts pass format checks.

Security boundary

This remains an obfuscation layer, not a privileged confidentiality boundary. Per-pack keys and decryption logic are shipped with the executable, and the plaintext payload exists in memory before execve. External device-bound key storage and AEAD are documented as a future format upgrade, not silently introduced here.

[litemars]

Hi @hansxia !

Thank you for PR! Would you be able to clean up a bit the markdowns that you are merging? Could you please merge the test files as well?