Refactor AIEngine and registry to improve function ID generation and support legacy names

- Updated AIEngine to normalize function names by replacing underscores with hyphens in generated function IDs for better consistency with frontend tracking.
- Enhanced registry to resolve function name aliases, allowing for backward compatibility with legacy function names when retrieving function instances.

backend/igny8_core/ai/registry.py

@@ -54,7 +54,15 @@ def list_functions() -> list:
 
 def get_function_instance(name: str) -> Optional[BaseAIFunction]:
     """Get function instance by name - lazy loads if needed"""
-    fn_class = get_function(name)
+    # Resolve alias first to support legacy function names
+    try:
+        from igny8_core.ai.settings import FUNCTION_ALIASES
+    except ImportError:
+        FUNCTION_ALIASES = {}
+    
+    actual_name = FUNCTION_ALIASES.get(name, name)
+    
+    fn_class = get_function(actual_name)
     if fn_class:
         return fn_class()
     return None