refactor: remove native vibra library and replace with Kotlin implementation

[kairosci]

Summary

• Removes native C++ vibra_fp library and FFTW3 dependency
• Replaces with pure Kotlin implementation in ShazamSignatureGenerator.kt
• Updates build.gradle.kts to remove NDK and CMake configuration
• Removes setup-fftw GitHub action

This simplifies the build process and removes the native library dependency.

Problem

The native vibra_fp library requires FFTW3 and adds complexity to the build system.

Solution

Replace the native implementation with a pure Kotlin port of the Shazam signature algorithm.

Testing

Build verified successfully.

[moonpic]

Hasn't this already been done in? ac8b2b5

[kairosci]

I don't think so, it's not in the codebase, otherwise it wouldn't track changes.