Enhance LLM and SwarmUI integration with improved configuration options

- Updated `env.example` and `gpu-rent.vars.example` to include new variables for LLM runtime and SwarmUI options.
- Refactored CLI commands to support interactive selection of LLM runtime and workload type (SwarmUI, LLM, or both).
- Improved access link generation to handle cases where SwarmUI is disabled, providing clearer user feedback.
- Enhanced provisioning logic to conditionally bootstrap SwarmUI based on user configuration, allowing for LLM-only setups.
- Updated documentation across multiple files to reflect changes in LLM integration, CLI usage, and configuration management.

src/gpu_rent/idle_killer.py

@@ -106,7 +106,7 @@ def install_units(cfg: Config, host: str, log: Log) -> None:
     )
     service = f"""[Unit]
 Description=gpu-rent idle-killer (one shot)
-After=network-online.target swarmui.service
+After=network-online.target
 
 [Service]
 Type=oneshot