docs: fix guide snippets and API examples

Author: nficano

docs/guides/delegation.md

@@ -28,7 +28,7 @@ server.RegisterAgent("orchestrator", async (ctx, ct) =>
         input: new { topic = "arcp" }, ct);
 
     var summary = await child.Result;
-    return new { summary = summary.Output };
+    return new { summary = summary.Result?.Result };
 });
 ```
 

docs/guides/job-events.md

@@ -34,7 +34,7 @@ server.RegisterAgent("researcher", async (ctx, ct) =>
     await ctx.ProgressAsync(current: 1, total: 3, message: "fetched", ct);
 
     await ctx.LogAsync("info", "Processing ...", ct);
-    await ctx.MetricAsync("cost.inference", 0.012m, unit: "USD", ct);
+    await ctx.MetricAsync("cost.inference", 0.012, unit: "USD", cancellationToken: ct);
 
     await ctx.ArtifactRefAsync(
         uri: "s3://bucket/report.pdf",

docs/guides/jobs.md

@@ -58,7 +58,7 @@ await foreach (var ev in handle.Events(cancellationToken))
 var result = await handle.Result;
 // result.Success == true
 // result.FinalStatus == "success"
-// result.Output — the agent's return value deserialized
+// result.Result?.Result — the agent's return value deserialized
 ```
 
 ## Await result directly