fix(vst): add versioned state format

[thorinf]

Summary

• write plugin state with a TR8S magic/version header
• load current versioned state plus legacy 5-word and 3-word per-gate layouts
• share state parsing between Processor and Controller restore paths
• reject truncated or unknown-version state instead of silently applying partial data

Tests

• make test (vst/tests)
• XCODE_VERSION=15.0 cmake -S vst -B vst/build -DCMAKE_BUILD_TYPE=Release
• XCODE_VERSION=15.0 cmake --build vst/build --target tram8-bridge (compiled and validator passed 47/47; final user VST3 install/link step failed due sandbox permission)
• git diff --check