Implements jeaddons CLI tool

Adds a CLI tool to copy files or folders from a git repository into the current project based on a registry.

The tool provides commands to:
- `add`: Copies files/folders based on registry entries.
- `list`: Lists available registry entries.

Registry entries are defined in `jeAddons/registry.py`.
The tool supports overriding the registry's ref and destination.

.idea/jeAddons.iml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="PYTHON_MODULE" version="4">
+  <component name="NewModuleRootManager">
+    <content url="file://$MODULE_DIR$">
+      <excludeFolder url="file://$MODULE_DIR$/.venv" />
+    </content>
+    <orderEntry type="jdk" jdkName="uv (jeAddons)" jdkType="Python SDK" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>