VNI: add encrypted PAC loading

[djrobx]

Summary

• Add encrypted PAC loading to libvni, including AES-CBC decryption and gzip/DEFLATE decoding without an external compression dependency.
• Preserve direct PAL/VNI loading and expose PAC/key inputs through the public loader API.
• Add an attribution comment for the DEFLATE decoder, referencing Mark Adler’s zlib puff.c implementation and the zlib license.

Validation

• Built the Release vni64.dll successfully on Windows with CMake/MSBuild.
• Installed and exercised the resulting PAC path with the Fish Tales FT_2.0.pac colorization.

This branch is based on the SAM palette-selection work already present in #9

[djrobx]

Closing in favor of decryption tool, to keep configuration path simpler.