fix(cli): list --port in --help for promptargs ui (#374)

changelog.d/fixed-374-help-port-flag.md

@@ -0,0 +1 @@
+`promptargs --help` now lists `--port=N` in both the `ui` subcommand usage line and the flags block, documenting the port flag that users need when the default port 3700 is in use. (#374)

src/cli.test.ts

@@ -105,6 +105,7 @@ test('help subcommand and --help flag print usage', () => {
     assert.strictEqual(res.status, 0, `exit code for ${arg}`);
     assert.match(res.stdout, /Usage:/);
     assert.match(res.stdout, /Flags \(place after the template name; -h\/--help works anywhere\):/);
+    assert.match(res.stdout, /--port=N/);
   }
   rmSync(dirname(cwd), { recursive: true, force: true });
 });

src/cli.ts

@@ -33,7 +33,7 @@ Usage:
   promptargs init                      Create .prompts/ with examples
   promptargs show <template>           Preview a template
   promptargs env                       Show auto-detected variable values
-  promptargs ui                        Open the builder UI in your browser
+  promptargs ui [--port=N]             Open the builder UI in your browser
   promptargs help                      Show this help
 
 Flags (place after the template name; -h/--help works anywhere):
@@ -43,6 +43,7 @@ Flags (place after the template name; -h/--help works anywhere):
   --status            Print status line only (for IDE integration)
   -h, --help          Show this help
   --var value         Same as --var=value (switches above take no value)
+  --port=N            Port for "promptargs ui" (default 3700)
 
 Array values:
   --file=a.go,b.go    Comma-separated → one run per value