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.TemplateEngine/TemplateService.cs

@@ -687,6 +687,8 @@ public class TemplateService
         existing.TriggerType = proposed.TriggerType;
         existing.TriggerConfiguration = proposed.TriggerConfiguration;
         existing.MinTimeBetweenRuns = proposed.MinTimeBetweenRuns;
+        // M2.5 (#9): per-script execution timeout is an overridable field.
+        existing.ExecutionTimeoutSeconds = proposed.ExecutionTimeoutSeconds;
         existing.ParameterDefinitions = proposed.ParameterDefinitions;
         existing.ReturnDefinition = proposed.ReturnDefinition;
         existing.IsLocked = proposed.IsLocked;
@@ -1013,6 +1015,7 @@ public class TemplateService
                 ParameterDefinitions = script.ParameterDefinitions,
                 ReturnDefinition = script.ReturnDefinition,
                 MinTimeBetweenRuns = script.MinTimeBetweenRuns,
+                ExecutionTimeoutSeconds = script.ExecutionTimeoutSeconds,
                 IsInherited = true,
                 LockedInDerived = false,
             });