Remove the dedicated `zig build lib-vt` step and replace it with a
`-Demit-lib-vt` build option. This fixes two problems:
1. We can default XCFramework, app, etc. steps to false if emit-lib-vt
is true, so that the lib-vt build doesn't pull in unrelated
artifacts. **Most importantly, lib-vt alone can be build without
full Xcode installations.**
2. We can build lib-vt as part of a bundle with other artifacts if we
really want.
Map CMake release build types (Release, MinSizeRel, RelWithDebInfo)
to -Doptimize=ReleaseFast so that zig build automatically produces
optimized builds when CMake is configured for a release variant.
Debug builds remain unaffected, letting Zig use its default Debug
optimization level.
Add a top-level CMakeLists.txt that wraps `zig build lib-vt` so that
CMake-based downstream projects can consume libghostty-vt without
needing to interact with the Zig build system directly. A custom
command triggers the zig build during `cmake --build`, and the
resulting shared library is exposed as an IMPORTED target.
Downstream projects can pull in the library via FetchContent, which
fetches the source and builds it as part of their own CMake build, or
via find_package after a manual install step. The package config
template in dist/cmake/ sets up the ghostty-vt::ghostty-vt target
with proper include paths and macOS rpath handling.
A c-vt-cmake example demonstrates the FetchContent workflow, creating
a terminal, writing VT sequences, and formatting the output as plain
text. CI is updated to auto-discover and build CMake-based examples
alongside the existing Zig-based ones.
Mitchell Hashimoto