Add FreeBSD build targets so OpenTUI's Zig core can be built natively.
Applied to the OpenTUI source tree by post-patch.

--- packages/native/build.zig.orig
+++ packages/native/build.zig
@@ -27,6 +27,8 @@
     .{ .zig_target = "aarch64-macos.13.0", .output_name = "aarch64-macos", .description = "macOS aarch64 (Apple Silicon)" },
     .{ .zig_target = "x86_64-windows-gnu", .output_name = "x86_64-windows", .description = "Windows x86_64" },
     .{ .zig_target = "aarch64-windows-gnu", .output_name = "aarch64-windows", .description = "Windows aarch64" },
+    .{ .zig_target = "x86_64-freebsd", .output_name = "x86_64-freebsd", .description = "FreeBSD x86_64" },
+    .{ .zig_target = "aarch64-freebsd", .output_name = "aarch64-freebsd", .description = "FreeBSD aarch64" },
 };
 
 const DEFAULT_MACOS_SDK_PATH = "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk";