Add user plugin directory to Python path

src/damaris/__init__.py

@@ -15,5 +15,13 @@
 
 ## module contents
 #
-__version__ = "0.22"
+__version__ = "0.23"
 __all__=["experiments", "data", "gui"]
+
+import sys
+import os
+
+# Add user plugin directory to Python path (highest priority)
+_plugin_dir = os.path.expanduser("~/.config/damaris/plugin")
+if os.path.isdir(_plugin_dir) and _plugin_dir not in sys.path:
+    sys.path.insert(0, _plugin_dir)