* chat: add support for agent plugin sources
- Adds support for agent plugins to reference sources as specified in
PLUGIN_SOURCES.md, enabling installation from GitHub, npm, pip, and
other package registries
- Integrates source parsing and validation into the plugin installation
service and repository service
- Adds comprehensive test coverage for plugin source handling and
installation from various sources
- Creates PLUGIN_SOURCES.md documentation describing how to specify
plugin source configurations
(Commit message generated by Copilot)
* comments
* windows fixes and fault handling
* fix tests