perf(templates): descendant reconcile loads only the subtree + chain (ScadaBridge#86)

TemplateService.ReconcileDescendantsAsync - run after every base member
add/update/delete, template and native-alarm-source alike - loaded the whole
tracked template graph (every template, member and script body) on each call,
which after #66 was the dominant cost of those paths. It now calls the new
ITemplateEngineRepository.GetTemplateReconcileClosureAsync: the same tracked,
fully-included shape as GetAllTemplatesAsync, restricted to the edited
template's derived subtree plus its own inheritance chain. The reconcile is
inheritance-only (TemplateInheritanceResolver never follows compositions) and
every descendant's chain runs through the edited template, so that set is
everything it reads.

The walk (Commons TemplateReconcileClosure, the descendant-direction twin of
#66's TemplateAnalysisClosure) loads one children batch per subtree depth and
one batch per ancestor level, terminates on parent cycles and stops at
dangling parents. A template with no children - the common case - costs one
empty probe and loads nothing.

Evidence:
- TemplateReconcileClosureTests: for every template of a graph with a deep
  subtree, an ancestor above the edited template, a composed module,
  look-alike unrelated trees, a parent cycle and a dangling parent, the
  closure-backed reconcile issues exactly the writes (add/update/delete,
  audit, save) of the old whole-graph reconcile, and the resolver answers
  identically for every descendant. Fails with the old service (whole-graph
  load wired to throw) and with the ancestor walk removed (mutation-checked).
- TemplateReconcileClosureRepositoryTests (SQLite, recorded SQL): 5 templates
  / 10 attributes instead of 47 / 94, tracked with script bodies; a leaf costs
  one probe query and tracks nothing.
- TemplateServiceTests: attribute add + update propagate two levels down with
  GetAllTemplatesAsync wired to throw; existing propagation tests now run
  against the closure via ServeReconcileClosureFromFullGraph.

ResyncInheritedMembersAsync (operator action) still reads the whole graph.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

tests/ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests/TemplateAuditShapeTests.cs

@@ -24,6 +24,7 @@ public class TemplateAuditShapeTests
     {
         _repoMock.Setup(r => r.SaveChangesAsync(It.IsAny<CancellationToken>())).ReturnsAsync(1);
         _repoMock.ServeClosureFromFullGraph();
+        _repoMock.ServeReconcileClosureFromFullGraph();
         _auditMock
             .Setup(a => a.LogAsync(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>(),
                 It.IsAny<string>(), It.IsAny<string>(), It.IsAny<object?>(), It.IsAny<CancellationToken>()))