This change adds a basic C API that allows access to Gemma functionality from other programming languages. The functionality is exposed via a shared library (DLL on Windows), with C++ interfaces and a basic C# interop wrapper included.
To build the DLL, use the `windows-dll` preset, which includes the C and C++ sources as follows:
```
cmake --preset windows-dll
cmake --build --config Release --preset windows-dll -j 4
```
This should generate a `gemma.dll` in `<build-dir>/Release`.
To build for non-Windows, the appropriate C++ DLL linking will need to be done to generate a shared library for the target OS.
PiperOrigin-RevId: 750246272
The gemma.cpp Authors