feat: Add initial implementation of Vulnerability Resolver Jobs

- Created project for StellaOps.Scanner.Analyzers.Native.Tests with necessary dependencies.
- Documented roles and guidelines in AGENTS.md for Scheduler module.
- Implemented IResolverJobService interface and InMemoryResolverJobService for handling resolver jobs.
- Added ResolverBacklogNotifier and ResolverBacklogService for monitoring job metrics.
- Developed API endpoints for managing resolver jobs and retrieving metrics.
- Defined models for resolver job requests and responses.
- Integrated dependency injection for resolver job services.
- Implemented ImpactIndexSnapshot for persisting impact index data.
- Introduced SignalsScoringOptions for configurable scoring weights in reachability scoring.
- Added unit tests for ReachabilityScoringService and RuntimeFactsIngestionService.
- Created dotnet-filter.sh script to handle command-line arguments for dotnet.
- Established nuget-prime project for managing package downloads.

src/Findings/StellaOps.Findings.Ledger/Observability/LedgerMetrics.cs

@@ -15,6 +15,20 @@ internal static class LedgerMetrics
         "ledger_events_total",
         description: "Number of ledger events appended.");
 
+    private static readonly Histogram<double> ProjectionApplySeconds = Meter.CreateHistogram<double>(
+        "ledger_projection_apply_seconds",
+        unit: "s",
+        description: "Duration to apply a ledger event to the finding projection.");
+
+    private static readonly Histogram<double> ProjectionLagSeconds = Meter.CreateHistogram<double>(
+        "ledger_projection_lag_seconds",
+        unit: "s",
+        description: "Lag between ledger recorded_at and projection application time.");
+
+    private static readonly Counter<long> ProjectionEventsTotal = Meter.CreateCounter<long>(
+        "ledger_projection_events_total",
+        description: "Number of ledger events applied to projections.");
+
     public static void RecordWriteSuccess(TimeSpan duration, string? tenantId, string? eventType, string? source)
     {
         var tags = new TagList
@@ -27,4 +41,25 @@ internal static class LedgerMetrics
         WriteLatencySeconds.Record(duration.TotalSeconds, tags);
         EventsTotal.Add(1, tags);
     }
+
+    public static void RecordProjectionApply(
+        TimeSpan duration,
+        double lagSeconds,
+        string? tenantId,
+        string? eventType,
+        string? policyVersion,
+        string? evaluationStatus)
+    {
+        var tags = new TagList
+        {
+            { "tenant", tenantId ?? string.Empty },
+            { "event_type", eventType ?? string.Empty },
+            { "policy_version", policyVersion ?? string.Empty },
+            { "evaluation_status", evaluationStatus ?? string.Empty }
+        };
+
+        ProjectionApplySeconds.Record(duration.TotalSeconds, tags);
+        ProjectionLagSeconds.Record(lagSeconds, tags);
+        ProjectionEventsTotal.Add(1, tags);
+    }
 }