feat: add Hyperspace Pods NixOS module and enable on lazyworkhorse

Hyperspace Pods let multiple machines pool their GPUs into one private
P2P mesh AI cluster. Models are split across all connected GPUs —
e.g. two machines with 16GB VRAM each can run Qwen 3.5 32B together.

Changes:
- Add modules/nixos/services/hyperspace.nix — NixOS module that:
  * Fetches the Hyperspace CLI binary (v5.45.30) via fetchurl
  * Sets up systemd service for the agent
  * Opens firewall ports (libp2p 4001, chain 30301, API 8080)
  * Configures GPU passthrough for AMD MI50 (ROCm)
- Register module in flake.nix for lazyworkhorse
- Enable hyperspace service on lazyworkhorse (ai-worker user, port 8080)

Usage after deployment:
  hyperspace pod create "tdnde-lab"   # create pod
  hyperspace pod invite                # share invite with cyt-pi
  curl http://localhost:8080/v1/chat/completions  # OpenAI API

See skill: nixos-hyperspace-pods

flake.nix

@@ -61,6 +61,7 @@
               ./modules/nixos/services/open_code_server.nix
               ./modules/nixos/services/ollama_init_custom_models.nix
               ./modules/nixos/services/openclaw_node.nix
+              ./modules/nixos/services/hyperspace.nix
               ./users/gortium.nix
               ./users/ai-worker.nix
             ];