c api: add ghostty_info to get metadata about the build

src/main_c.zig

@@ -9,6 +9,7 @@
 const std = @import("std");
 const assert = std.debug.assert;
 const builtin = @import("builtin");
+const build_config = @import("build_config.zig");
 const main = @import("main.zig");
 const apprt = @import("apprt.zig");
 
@@ -23,6 +24,20 @@ pub const std_options = main.std_options;
 pub usingnamespace @import("config.zig").CAPI;
 pub usingnamespace apprt.runtime.CAPI;
 
+/// ghostty_info_s
+const Info = extern struct {
+    mode: BuildMode,
+    version: [*]const u8,
+    version_len: usize,
+
+    const BuildMode = enum(c_int) {
+        debug,
+        release_safe,
+        release_fast,
+        release_small,
+    };
+};
+
 /// Initialize ghostty global state. It is possible to have more than
 /// one global state but it has zero practical benefit.
 export fn ghostty_init() c_int {
@@ -30,3 +45,16 @@ export fn ghostty_init() c_int {
     main.state.init();
     return 0;
 }
+
+export fn ghostty_info() Info {
+    return .{
+        .mode = switch (builtin.mode) {
+            .Debug => .debug,
+            .ReleaseSafe => .release_safe,
+            .ReleaseFast => .release_fast,
+            .ReleaseSmall => .release_small,
+        },
+        .version = build_config.version_string.ptr,
+        .version_len = build_config.version_string.len,
+    };
+}