cli/gtk: replace @hasDecl for performAction-style API

Instead of using @hasDecl, use a performAction-stype API. The C
interface for interfacing with macOS (or any other apprt where Ghostty
is embedded) is unfinished.

src/apprt/none.zig

@@ -1,6 +1,21 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
 const internal_os = @import("../os/main.zig");
+const apprt = @import("../apprt.zig");
 pub const resourcesDir = internal_os.resourcesDir;
+
 pub const App = struct {};
 pub const Surface = struct {};
 /// Functions for inter-process communication.
-pub const IPC = struct {};
+pub const IPC = struct {
+    /// Always return false as there is no apprt to communicate with.
+    pub fn sendIPC(
+        _: Allocator,
+        _: apprt.ipc.Target,
+        comptime action: apprt.ipc.Action.Key,
+        _: apprt.ipc.Action.Value(action),
+    ) !bool {
+        return false;
+    }
+};