setup basic doxygen for docs

We may not stick with Doxygen, but it gives us something to start with.

Doxyfile

@@ -0,0 +1,28 @@
+# Doxyfile 1.13.2
+
+DOXYFILE_ENCODING      = UTF-8
+PROJECT_NAME           = "libghostty"
+INPUT                  = include/ghostty-vt.h
+INPUT_ENCODING         = UTF-8
+RECURSIVE              = NO
+
+#---------------------------------------------------------------------------
+# HTML Output
+#---------------------------------------------------------------------------
+
+GENERATE_HTML          = YES
+HTML_OUTPUT            = zig-out/share/ghostty/doc/libghostty
+
+#---------------------------------------------------------------------------
+# Man Output
+#---------------------------------------------------------------------------
+
+GENERATE_MAN           = YES
+MAN_OUTPUT             = zig-out/share/man
+MAN_EXTENSION          = .3
+
+#---------------------------------------------------------------------------
+# Other Output
+#---------------------------------------------------------------------------
+
+GENERATE_LATEX         = NO

nix/devShell.nix

@@ -3,6 +3,7 @@
   lib,
   stdenv,
   bashInteractive,
+  doxygen,
   nushell,
   appstream,
   flatpak-builder,
@@ -89,6 +90,7 @@ in
     packages =
       [
         # For builds
+        doxygen
         jq
         llvmPackages_latest.llvm
         minisign

src/lib_vt.zig

@@ -66,9 +66,9 @@ pub const TabClear = terminal.TabClear;
 pub const Attribute = terminal.Attribute;
 
 comptime {
-    if (terminal.is_c_lib) {
-        _ = terminal.c_api;
-    }
+    // If we're building the C library (vs. the Zig module) then
+    // we want to reference the C API so that it gets exported.
+    if (terminal.is_c_lib) _ = terminal.c_api;
 }
 
 test {