fix(cmdline): make cmdline work without PIL dependency

- Refactor controller to not require importing engine.layers (which imports PIL)
- Add set_effect_chain_ref for external chain registration
- Fix cmdline to use new ref mechanism

engine/effects/controller.py

@@ -1,11 +1,24 @@
 from engine.effects.performance import get_monitor
 from engine.effects.registry import get_registry
 
+_effect_chain_ref = None
+
 
 def _get_effect_chain():
-    from engine.layers import get_effect_chain as _chain
+    global _effect_chain_ref
+    if _effect_chain_ref is not None:
+        return _effect_chain_ref
+    try:
+        from engine.layers import get_effect_chain as _chain
 
-    return _chain()
+        return _chain()
+    except Exception:
+        return None
+
+
+def set_effect_chain_ref(chain) -> None:
+    global _effect_chain_ref
+    _effect_chain_ref = chain
 
 
 def handle_effects_command(cmd: str) -> str: