feat(telemetry): export the site script compile-cache eviction counter as a Meter (ScadaBridge#68)

SiteScriptCompileCache now records each eviction sweep on scadabridge.site.script_compile_cache.evictions
(ScadaBridgeTelemetry). It rides the existing ZB.MOM.WW.ScadaBridge meter, which is already in
SiteServiceRegistration.ObservedMeters, so no new allowlist entry is needed; a Host test pins that
the meter stays allowlisted.

tests/ZB.MOM.WW.ScadaBridge.Host.Tests/SiteLocalDbWiringTests.cs

@@ -245,6 +245,17 @@ public class SiteLocalDbWiringTests : IDisposable
         Assert.Contains(LocalDbMetrics.MeterName, SiteServiceRegistration.ObservedMeters);
     }
 
+    /// <summary>Verifies that the ScadaBridge application meter (carrying the compile-cache eviction counter) is exported.</summary>
+    [Fact]
+    public void Site_Telemetry_Allowlists_TheScadaBridgeMeter()
+    {
+        // ScadaBridge#68: scadabridge.site.script_compile_cache.evictions lives on this meter; an
+        // unlisted meter is dropped silently (ZbTelemetryOptions.Meters is an allowlist).
+        Assert.Contains(
+            ZB.MOM.WW.ScadaBridge.Commons.Observability.ScadaBridgeTelemetry.MeterName,
+            SiteServiceRegistration.ObservedMeters);
+    }
+
     /// <summary>Verifies that the Phase 2 tables are created in the consolidated LocalDb file.</summary>
     [Fact]
     public void Site_LocalDb_CreatesThePhase2Tables_InTheConsolidatedFile()