feat(dev): add gastown multi-agent workspace manager

- Add gastown flake input (non-flake, source only)
- Build gastown package using buildGoModule in development role
- Configure renovate for daily updates of gastown and beads
- Binary: gt (Gas Town CLI by Steve Yegge)

home/roles/development/default.nix

@@ -11,6 +11,23 @@ let
     vendorHash = "sha256-YU+bRLVlWtHzJ1QPzcKJ70f+ynp8lMoIeFlm+29BNPE=";
   });
 
+  # Gastown - multi-agent workspace manager (no upstream flake.nix yet)
+  # Source is tracked via flake input for renovate updates
+  gastownPackage = pkgs.buildGoModule {
+    pname = "gastown";
+    version = "unstable-${builtins.substring 0 8 globalInputs.gastown.rev or "unknown"}";
+    src = globalInputs.gastown;
+    vendorHash = "sha256-ripY9vrYgVW8bngAyMLh0LkU/Xx1UUaLgmAA7/EmWQU=";
+    subPackages = [ "cmd/gt" ];
+    doCheck = false;
+    meta = with lib; {
+      description = "Gas Town - multi-agent workspace manager by Steve Yegge";
+      homepage = "https://github.com/steveyegge/gastown";
+      license = licenses.mit;
+      mainProgram = "gt";
+    };
+  };
+
   # Fetch the claude-plugins repository (for humanlayer commands/agents)
   # Update the rev to get newer versions of the commands
   claudePluginsRepo = builtins.fetchGit {
@@ -44,6 +61,7 @@ in
   config = mkIf cfg.enable {
     home.packages = [
       beadsPackage
+      gastownPackage
       pkgs.unstable.claude-code
       pkgs.unstable.claude-code-router
       pkgs.unstable.codex