feat: add llmx config, update arty references to dev.pivoine.art

- Add .llmx/ directory for LLM configuration
- Update bin repo URL to dev.pivoine.art
- Add home-llmx reference to arty.yml
- Add uv/install script for Python package manager
- Update debian/install with additional packages
- Add debian/update script for non-free repos
- Update README.md to reflect changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -21,6 +21,9 @@
 !arty.yml
 !signature.txt
 
+!/.llmx/
+!/.llmx/config.toml
+
 !/.config/
 !/.config/zed/
 !/.config/zed/settings.json