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/remote/idle_killer.py

@@ -236,7 +236,10 @@ def main() -> int:
         return 0
 
     swarm_url = str(creds.get("swarm_url") or "http://127.0.0.1:7801")
-    busy, detail = swarm_busy(swarm_url)
+    if (DATA / ".gpu-rent-llm-only").is_file():
+        busy, detail = False, "llm-only (swarm skip)"
+    else:
+        busy, detail = swarm_busy(swarm_url)
     if busy:
         write_ts(IDLE_SINCE, None)
         log(f"busy: {detail}")