feat(dev-orchestrator): add NixOS home-manager module

- New module: modules/home-manager/dev-orchestrator/
- Wraps script via writeShellApplication, git as runtime dep
- opencode + openspec already in PATH via existing modules
- Enabled in jpporta-nixos home.nix

After rebuild: dev-orchestrator available in PATH

hosts/jpporta-nixos/home.nix

@@ -31,6 +31,7 @@
     ../../modules/home-manager/pi
     ../../modules/home-manager/tmux
     ../../modules/home-manager/openspec
+    ../../modules/home-manager/dev-orchestrator
     ../../modules/home-manager/power-profiles
     ../../modules/home-manager/ntfy-notify
     ../../modules/home-manager/pinentry
@@ -94,6 +95,7 @@
       enable = true;
     };
     openspec.enable = true;
+    dev-orchestrator.enable = true;
     power-profiles.enable = true;
     ntfy-notify.enable = true;
     bitwarden.enable = true;