feat(metrics): Add new histograms for chunk latency, results, and sources in AdvisoryAiMetrics

feat(telemetry): Record chunk latency, result count, and source count in AdvisoryAiTelemetry

fix(endpoint): Include telemetry source count in advisory chunks endpoint response

test(metrics): Enhance WebServiceEndpointsTests to validate new metrics for chunk latency, results, and sources

refactor(tests): Update test utilities for Deno language analyzer tests

chore(tests): Add performance tests for AdvisoryGuardrail with scenarios and blocked phrases

docs: Archive Sprint 137 design document for scanner and surface enhancements

src/Concelier/StellaOps.Concelier.WebService/Services/AdvisoryAiTelemetry.cs

@@ -33,6 +33,18 @@ internal sealed class AdvisoryAiTelemetry : IAdvisoryAiTelemetry
         AdvisoryAiMetrics.ChunkRequestCounter.Add(1,
             AdvisoryAiMetrics.BuildChunkRequestTags(tenant, result, telemetry.Truncated, telemetry.CacheHit));
 
+        AdvisoryAiMetrics.ChunkLatencyHistogram.Record(
+            telemetry.Duration.TotalMilliseconds,
+            AdvisoryAiMetrics.BuildLatencyTags(tenant, result, telemetry.Truncated, telemetry.CacheHit));
+
+        AdvisoryAiMetrics.ChunkResultHistogram.Record(
+            telemetry.ChunkCount,
+            AdvisoryAiMetrics.BuildChunkResultTags(tenant, result, telemetry.Truncated));
+
+        AdvisoryAiMetrics.ChunkSourceHistogram.Record(
+            telemetry.SourceCount,
+            AdvisoryAiMetrics.BuildSourceTags(tenant, result));
+
         if (telemetry.CacheHit)
         {
             AdvisoryAiMetrics.ChunkCacheHitCounter.Add(1,
@@ -56,13 +68,15 @@ internal sealed class AdvisoryAiTelemetry : IAdvisoryAiTelemetry
         }
 
         _logger.LogInformation(
-            "Advisory chunk request for tenant {Tenant} key {Key} returned {Chunks} chunks across {Sources} sources (truncated: {Truncated}, cacheHit: {CacheHit}, durationMs: {Duration}).",
+            "Advisory chunk request for tenant {Tenant} key {Key} returned {Chunks} chunks across {Sources} sources (observationsLoaded: {Observations}, truncated: {Truncated}, cacheHit: {CacheHit}, guardrailBlocks: {GuardrailBlocks}, durationMs: {Duration}).",
             tenant,
             telemetry.AdvisoryKey,
             telemetry.ChunkCount,
+            telemetry.SourceCount,
             telemetry.ObservationCount,
             telemetry.Truncated,
             telemetry.CacheHit,
+            telemetry.TotalGuardrailBlocks,
             telemetry.Duration.TotalMilliseconds.ToString("F2", CultureInfo.InvariantCulture));
     }
 
@@ -118,6 +132,7 @@ internal sealed record AdvisoryAiChunkRequestTelemetry(
     bool Truncated,
     bool CacheHit,
     int ObservationCount,
+    int SourceCount,
     int ChunkCount,
     TimeSpan Duration,
     IReadOnlyDictionary<AdvisoryChunkGuardrailReason, int> GuardrailCounts)