infra(api-gdext): 🧱 Update Rust GDExtension API functions and bindings for Godot Engine compatibility

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/simulator/api-gdext/src/lib.rs

@@ -3776,6 +3776,23 @@ impl GdGameState {
         true
     }
 
+    /// List every registered AI controller id (sorted, ascending).
+    /// Bridges `mc_player_api::registered_ids` to GDScript so the
+    /// game-setup screen (Stage 8) can populate its per-slot
+    /// "AI Controller" dropdowns without hardcoding the id list.
+    ///
+    /// At engine boot the registry contains `"scripted:default"`;
+    /// `ModLoader` (Stage 5) registers additional ids before this
+    /// is read.
+    #[func]
+    fn registered_controller_ids() -> PackedStringArray {
+        let mut out = PackedStringArray::new();
+        for id in mc_player_api::registered_ids() {
+            out.push(&GString::from(id));
+        }
+        out
+    }
+
     /// Current turn number.
     #[func]
     fn turn(&self) -> i64 {