feat(metrics): Implement scan metrics repository and PostgreSQL integration

- Added IScanMetricsRepository interface for scan metrics persistence and retrieval.
- Implemented PostgresScanMetricsRepository for PostgreSQL database interactions, including methods for saving and retrieving scan metrics and execution phases.
- Introduced methods for obtaining TTE statistics and recent scans for tenants.
- Implemented deletion of old metrics for retention purposes.

test(tests): Add SCA Failure Catalogue tests for FC6-FC10

- Created ScaCatalogueDeterminismTests to validate determinism properties of SCA Failure Catalogue fixtures.
- Developed ScaFailureCatalogueTests to ensure correct handling of specific failure modes in the scanner.
- Included tests for manifest validation, file existence, and expected findings across multiple failure cases.

feat(telemetry): Integrate scan completion metrics into the pipeline

- Introduced IScanCompletionMetricsIntegration interface and ScanCompletionMetricsIntegration class to record metrics upon scan completion.
- Implemented proof coverage and TTE metrics recording with logging for scan completion summaries.

src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core/ScanCompletionMetricsIntegration.cs

@@ -0,0 +1,111 @@
+// -----------------------------------------------------------------------------
+// ScanCompletionMetricsIntegration.cs
+// Sprint: SPRINT_3401_0001_0001_determinism_scoring_foundations
+// Task: DET-3401-007
+// Description: Integrates proof coverage calculation into scan completion pipeline
+// -----------------------------------------------------------------------------
+
+using Microsoft.Extensions.Logging;
+
+namespace StellaOps.Telemetry.Core;
+
+/// <summary>
+/// Integrates proof coverage metrics into the scan completion pipeline.
+/// </summary>
+public interface IScanCompletionMetricsIntegration
+{
+    /// <summary>
+    /// Records metrics at scan completion.
+    /// </summary>
+    void OnScanCompleted(ScanCompletionData data);
+}
+
+/// <summary>
+/// Data required for scan completion metrics calculation.
+/// </summary>
+public sealed record ScanCompletionData
+{
+    public required string TenantId { get; init; }
+    public required string SurfaceId { get; init; }
+    public required string ScanId { get; init; }
+
+    // Finding counts
+    public required int TotalFindings { get; init; }
+    public required int FindingsWithReceipts { get; init; }
+
+    // VEX counts
+    public required int TotalVexItems { get; init; }
+    public required int VexWithReceipts { get; init; }
+
+    // Reachability counts
+    public required int TotalReachableFindings { get; init; }
+    public required int ReachableWithProofs { get; init; }
+
+    // Timing
+    public required DateTimeOffset StartedAt { get; init; }
+    public required DateTimeOffset CompletedAt { get; init; }
+
+    /// <summary>
+    /// Total scan duration in milliseconds.
+    /// </summary>
+    public int DurationMs => (int)(CompletedAt - StartedAt).TotalMilliseconds;
+}
+
+public sealed class ScanCompletionMetricsIntegration : IScanCompletionMetricsIntegration
+{
+    private readonly ProofCoverageMetrics _proofCoverage;
+    private readonly TimeToEvidenceMetrics _tteMetrics;
+    private readonly ILogger<ScanCompletionMetricsIntegration> _logger;
+
+    public ScanCompletionMetricsIntegration(
+        ProofCoverageMetrics proofCoverage,
+        TimeToEvidenceMetrics tteMetrics,
+        ILogger<ScanCompletionMetricsIntegration> logger)
+    {
+        _proofCoverage = proofCoverage ?? throw new ArgumentNullException(nameof(proofCoverage));
+        _tteMetrics = tteMetrics ?? throw new ArgumentNullException(nameof(tteMetrics));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    public void OnScanCompleted(ScanCompletionData data)
+    {
+        ArgumentNullException.ThrowIfNull(data);
+
+        // Record proof coverage metrics
+        _proofCoverage.RecordScanCoverage(
+            tenantId: data.TenantId,
+            surfaceId: data.SurfaceId,
+            findingsWithReceipts: data.FindingsWithReceipts,
+            totalFindings: data.TotalFindings,
+            vexWithReceipts: data.VexWithReceipts,
+            totalVex: data.TotalVexItems,
+            reachableWithProofs: data.ReachableWithProofs,
+            totalReachable: data.TotalReachableFindings);
+
+        // Record TTE metrics
+        _tteMetrics.RecordScanDuration(
+            tenantId: data.TenantId,
+            surfaceId: data.SurfaceId,
+            durationMs: data.DurationMs,
+            findingCount: data.TotalFindings);
+
+        // Log summary
+        var allCoverage = ComputePercentage(data.FindingsWithReceipts, data.TotalFindings);
+        var vexCoverage = ComputePercentage(data.VexWithReceipts, data.TotalVexItems);
+        var reachCoverage = ComputePercentage(data.ReachableWithProofs, data.TotalReachableFindings);
+
+        _logger.LogInformation(
+            "Scan {ScanId} completed. TTE={DurationMs}ms, Proof coverage: all={AllCov}%, vex={VexCov}%, reachable={ReachCov}%",
+            data.ScanId,
+            data.DurationMs,
+            allCoverage,
+            vexCoverage,
+            reachCoverage);
+    }
+
+    private static int ComputePercentage(int numerator, int denominator)
+    {
+        if (denominator <= 0) return 100;
+        return (numerator * 100) / denominator;
+    }
+}