feat(shorebird_cli)!: hard-error on shorebird login:ci (#3775)

packages/shorebird_cli/lib/src/commands/login_ci_command.dart

@@ -4,25 +4,25 @@ import 'package:shorebird_cli/src/shorebird_command.dart';
 
 /// {@template login_ci_command}
 /// `shorebird login:ci`
-/// Deprecated — directs users to API keys instead.
+/// Removed — directs users to API keys instead.
 /// {@endtemplate}
 class LoginCiCommand extends ShorebirdCommand {
   @override
-  String get description => 'Login as a CI user (deprecated).';
+  String get description => 'Removed — use API keys instead.';
 
   @override
   String get name => 'login:ci';
 
   @override
   Future<int> run() async {
-    logger.info(
+    logger.err(
       '''
-${lightYellow.wrap('⚠ shorebird login:ci is deprecated.')}
+shorebird login:ci has been replaced by API keys.
 
-To authenticate in CI, create an API key at ${link(uri: Uri.parse('https://console.shorebird.dev'))} and set it as your ${lightCyan.wrap('SHOREBIRD_TOKEN')} environment variable.
+Create an API key at ${link(uri: Uri.parse('https://console.shorebird.dev'))} and set it as your ${lightCyan.wrap('SHOREBIRD_TOKEN')} environment variable.
 
-Existing tokens from login:ci will continue to work for now, but will stop working in a future release.''',
+Learn more: ${link(uri: Uri.parse('https://docs.shorebird.dev/account/api-keys/'))}''',
     );
-    return ExitCode.success.code;
+    return ExitCode.usage.code;
   }
 }

packages/shorebird_cli/test/src/commands/login_ci_command_test.dart

@@ -36,22 +36,23 @@ void main() {
     });
 
     test('has correct description', () {
-      expect(command.description, contains('deprecated'));
+      expect(command.description, contains('Removed'));
     });
 
-    test('shows deprecation message and exits with code 0', () async {
+    test('errors with usage exit code and points to API keys', () async {
       final result = await runWithOverrides(command.run);
 
-      expect(result, equals(ExitCode.success.code));
+      expect(result, equals(ExitCode.usage.code));
 
       final captured = verify(
-        () => logger.info(captureAny()),
+        () => logger.err(captureAny()),
       ).captured;
 
       final message = captured.single as String;
-      expect(message, contains('shorebird login:ci is deprecated'));
+      expect(message, contains('shorebird login:ci has been replaced'));
       expect(message, contains('console.shorebird.dev'));
       expect(message, contains('SHOREBIRD_TOKEN'));
+      expect(message, contains('docs.shorebird.dev/account/api-keys'));
     });
 
     test('does not trigger any auth flow', () async {