feat(esg): TimeoutSeconds in ExternalSystem UI form + Component-ExternalSystemGateway doc sync — closes the spec-drift gap

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Design/ExternalSystemForm.razor

@@ -62,6 +62,11 @@
                     <label class="form-label">Retry Delay (seconds)</label>
                     <input type="number" class="form-control" @bind="_retryDelaySeconds" min="0" />
                 </div>
+                <div class="mb-3">
+                    <label class="form-label">Timeout (seconds)</label>
+                    <input type="number" class="form-control" @bind="_timeoutSeconds" min="0" />
+                    <div class="form-text">0 = use gateway default</div>
+                </div>
 
                 @if (_formError != null)
                 {
@@ -85,6 +90,7 @@
     private string? _authConfig;
     private int _maxRetries = 3;
     private int _retryDelaySeconds = 5;
+    private int _timeoutSeconds;
     private string? _formError;
 
     private ExternalSystemDefinition? _existing;
@@ -112,6 +118,7 @@
                     _authConfig = _existing.AuthConfiguration;
                     _maxRetries = _existing.MaxRetries;
                     _retryDelaySeconds = (int)_existing.RetryDelay.TotalSeconds;
+                    _timeoutSeconds = _existing.TimeoutSeconds;
                 }
             }
             catch (Exception ex) { _formError = ex.Message; }
@@ -138,6 +145,7 @@
                 _existing.AuthConfiguration = _authConfig?.Trim();
                 _existing.MaxRetries = _maxRetries;
                 _existing.RetryDelay = TimeSpan.FromSeconds(_retryDelaySeconds);
+                _existing.TimeoutSeconds = _timeoutSeconds;
                 await ExternalSystemRepository.UpdateExternalSystemAsync(_existing);
             }
             else
@@ -146,7 +154,8 @@
                 {
                     AuthConfiguration = _authConfig?.Trim(),
                     MaxRetries = _maxRetries,
-                    RetryDelay = TimeSpan.FromSeconds(_retryDelaySeconds)
+                    RetryDelay = TimeSpan.FromSeconds(_retryDelaySeconds),
+                    TimeoutSeconds = _timeoutSeconds
                 };
                 await ExternalSystemRepository.AddExternalSystemAsync(es);
             }