feat(runtime): per-script execution timeout overriding the global default (#9)

Spec promised a per-script timeout but only the global ScriptExecutionTimeoutSeconds
existed. Add nullable TemplateScript.ExecutionTimeoutSeconds threaded through EF +
flattening (ResolvedScript) to ScriptExecutionActor/AlarmExecutionActor, which use
perScript ?? global for the execution CTS. Includes the EF migration for the new column.

src/ZB.MOM.WW.ScadaBridge.Transport/Import/BundleImporter.cs

@@ -2339,6 +2339,7 @@ public sealed class BundleImporter : IBundleImporter
                 ParameterDefinitions = s.ParameterDefinitions,
                 ReturnDefinition = s.ReturnDefinition,
                 MinTimeBetweenRuns = s.MinTimeBetweenRuns,
+                ExecutionTimeoutSeconds = s.ExecutionTimeoutSeconds,
                 Source = "Template",
             });
         }