fix: compositor handles wl_data_device_manager and wl_subcompositor

- get_data_device: stores wl_data_device in client object map
- get_subsurface: stores wl_subsurface in client object map
- data_device/subsurface requests accepted silently (Qt6 needs
  these proxies to exist for initialization even though we don't
  implement clipboard or subsurface compositing yet)

Instrumentation confirmed: setupConnection() completes with valid
registry=0x44f230. Crash is in Qt6 global binding path during
forceRoundTrip(), not in compositor protocol handling.

local/recipes/wayland/redbear-compositor/source/src/main.rs

@@ -401,6 +401,13 @@ const OBJECT_TYPE_WL_POINTER: u32 = 15;
 const OBJECT_TYPE_WL_KEYBOARD: u32 = 16;
 const OBJECT_TYPE_WL_DATA_DEVICE_MANAGER: u32 = 17;
 const OBJECT_TYPE_WL_SUBCOMPOSITOR: u32 = 18;
+const OBJECT_TYPE_WL_DATA_DEVICE: u32 = 19;
+const OBJECT_TYPE_WL_SUBSURFACE: u32 = 20;
+
+// wl_data_device_manager opcodes
+const WL_DATA_DEVICE_MANAGER_GET_DATA_DEVICE: u16 = 1;
+// wl_subcompositor opcodes
+const WL_SUBCOMPOSITOR_GET_SUBSURFACE: u16 = 1;
 
 struct Global {
     name: u32,
@@ -1078,13 +1085,49 @@ impl Compositor {
                 | OBJECT_TYPE_XDG_TOPLEVEL
                 | OBJECT_TYPE_WL_POINTER
                 | OBJECT_TYPE_WL_KEYBOARD
-                | OBJECT_TYPE_WL_DATA_DEVICE_MANAGER
-                | OBJECT_TYPE_WL_SUBCOMPOSITOR => {
-                    eprintln!(
-                        "redbear-compositor: unhandled opcode {} on object {}",
-                        opcode, object_id
-                    );
-                }
+                |                 OBJECT_TYPE_WL_DATA_DEVICE_MANAGER => match opcode {
+                    WL_DATA_DEVICE_MANAGER_GET_DATA_DEVICE => {
+                        if payload.len() >= 4 {
+                            let new_id = u32::from_le_bytes([
+                                payload[0], payload[1], payload[2], payload[3],
+                            ]);
+                            let mut clients = self.clients.lock().unwrap();
+                            if let Some(client) = clients.get_mut(&client_id) {
+                                client.objects.insert(new_id, OBJECT_TYPE_WL_DATA_DEVICE);
+                            }
+                        }
+                    }
+                    _ => {
+                        eprintln!(
+                            "redbear-compositor: unhandled data_device_manager opcode {} on object {}",
+                            opcode, object_id
+                        );
+                    }
+                },
+                OBJECT_TYPE_WL_SUBCOMPOSITOR => match opcode {
+                    WL_SUBCOMPOSITOR_GET_SUBSURFACE => {
+                        if payload.len() >= 4 {
+                            let new_id = u32::from_le_bytes([
+                                payload[0], payload[1], payload[2], payload[3],
+                            ]);
+                            let mut clients = self.clients.lock().unwrap();
+                            if let Some(client) = clients.get_mut(&client_id) {
+                                client.objects.insert(new_id, OBJECT_TYPE_WL_SUBSURFACE);
+                            }
+                        }
+                    }
+                    _ => {
+                        eprintln!(
+                            "redbear-compositor: unhandled subcompositor opcode {} on object {}",
+                            opcode, object_id
+                        );
+                    }
+                },
+                OBJECT_TYPE_WL_DATA_DEVICE | OBJECT_TYPE_WL_SUBSURFACE => {
+                    // Accept all requests silently — Qt6 needs these proxies
+                    // to exist for initialization but we don't implement
+                    // clipboard or subsurface compositing yet.
+                },
                 _ => {
                     eprintln!(
                         "redbear-compositor: unhandled object {} opcode {}",