Add comprehensive tests for plugin management and IPC functionality

- Introduced tests for the plugin catalogue installation and update flows in `test_plugin_catalogue_install.py`.
- Added unit tests for the GitHub Releases plugin client in `test_plugin_github_releases.py`.
- Implemented IPC tests for the plugin manager Unix socket protocol in `test_plugin_ipc.py`.
- Created lifecycle and installation tests for the plugin manager in `test_plugin_manager_lifecycle.py`.
- Added tests for plugin manifest parsing in `test_plugin_manifest.py`.
- Developed tests for plugin filesystem layout and state management in `test_plugin_storage.py`.

config.yaml.example

@@ -635,6 +635,19 @@ storage:
     # - 1 hour resolution for 1 year
 
 
+# Plugin manager (optional external process lifecycle)
+# plugins:
+#   # Master switch for the openhop-plugin-manager service (default: enabled when omitted)
+#   enabled: true
+#   # Install root (default: {storage.storage_dir}/plugins)
+#   # root: "/var/lib/openhop_repeater/plugins"
+#   # Unix domain socket used by Repeater HTTP → plugin manager IPC
+#   # socket: "/var/lib/openhop_repeater/plugin-manager.sock"
+  # Optional override for the curated catalogue (default: openhop-dev/openhop-plugin-catalogue)
+  # catalogue_url: "https://raw.githubusercontent.com/openhop-dev/openhop-plugin-catalogue/main/catalogue.json"
+
+
+
 mqtt_brokers:
   iata_code: "Test"  # e.g., "SFO", "LHR", "Test"
   status_interval: 300 # How often a status message is sent (in seconds)