feat: add a try_import helper for optional imports

Add a small try_import(module) helper that returns the imported module or None, so optional dependencies can be handled gracefully at the call site.

Author: ghostiee-11

lumen/util.py

@@ -493,6 +493,20 @@ def normalize_table_name(name: str) -> str:
     return re.sub(r'\W+', '_', name).strip('_').lower()
 
 
+def try_import(module: str):
+    """Attempt to import a module.
+
+    Returns
+    -------
+    module | None
+        The imported module if successful, otherwise None.
+    """
+    try:
+        return importlib.import_module(module)
+    except ImportError:
+        return None
+
+
 def try_import_xarray():
     """Import and return xarray, or None if xarray or xarray-sql is unavailable."""
     try: