fix(dw): 🐛 fail fast when portless alias registration fails

Previously logged to stderr and continued, leaving dev startup
proceeding with broken wtN.localhost URLs. Now calls fatal() so the
caller halts before downstream code uses the invalid alias.

scripts/dw/helpers/portless.ts

@@ -1,4 +1,4 @@
-import { sh, log } from "./shell.ts";
+import { sh, log, fatal } from "./shell.ts";
 import { aliasesFor } from "./ports.ts";
 import type { WorktreeAliases } from "../types.ts";
 
@@ -14,9 +14,7 @@ export function registerPortlessAliases(worktreeNum: number): WorktreeAliases {
 	] as const) {
 		const res = sh("portless", ["alias", name, String(port), "--force"]);
 		if (res.code !== 0) {
-			console.error(
-				`[dw] portless alias ${name} -> ${port} failed: ${res.stderr}`,
-			);
+			fatal(`portless alias ${name} -> ${port} failed: ${res.stderr}`);
 		}
 	}
 	log(