Fix RetrievedFromCache always showing False (#88) (#89)

RetrievedFromCache is an attribute on the StmtSimple XML element,
but the parser was reading it from the child QueryPlan element
where it never exists. Changed to read from stmtEl instead of
queryPlanEl.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: erikdarlingdata

src/PlanViewer.Core/Services/ShowPlanParser.cs

@@ -409,7 +409,7 @@ private static void ParseQueryPlanElements(PlanStatement stmt, XElement stmtEl,
         stmt.CachedPlanSizeKB = ParseLong(queryPlanEl.Attribute("CachedPlanSize")?.Value);
         stmt.DegreeOfParallelism = (int)ParseDouble(queryPlanEl.Attribute("DegreeOfParallelism")?.Value);
         stmt.NonParallelPlanReason = queryPlanEl.Attribute("NonParallelPlanReason")?.Value;
-        stmt.RetrievedFromCache = queryPlanEl.Attribute("RetrievedFromCache")?.Value is "true" or "1";
+        stmt.RetrievedFromCache = stmtEl.Attribute("RetrievedFromCache")?.Value is "true" or "1";
         stmt.CompileTimeMs = ParseLong(queryPlanEl.Attribute("CompileTime")?.Value);
         stmt.CompileMemoryKB = ParseLong(queryPlanEl.Attribute("CompileMemory")?.Value);
         stmt.CompileCPUMs = ParseLong(queryPlanEl.Attribute("CompileCPU")?.Value);