feat(telemetry): add telemetry client and services for tracking events

- Implemented TelemetryClient to handle event queuing and flushing to the telemetry endpoint.
- Created TtfsTelemetryService for emitting specific telemetry events related to TTFS.
- Added tests for TelemetryClient to ensure event queuing and flushing functionality.
- Introduced models for reachability drift detection, including DriftResult and DriftedSink.
- Developed DriftApiService for interacting with the drift detection API.
- Updated FirstSignalCardComponent to emit telemetry events on signal appearance.
- Enhanced localization support for first signal component with i18n strings.

src/Scanner/__Libraries/StellaOps.Scanner.Reachability/Boundary/BoundaryExtractionContext.cs

@@ -0,0 +1,90 @@
+// -----------------------------------------------------------------------------
+// BoundaryExtractionContext.cs
+// Sprint: SPRINT_3800_0002_0001_boundary_richgraph
+// Description: Context for boundary extraction with environment hints.
+// -----------------------------------------------------------------------------
+
+using System;
+using System.Collections.Generic;
+using StellaOps.Scanner.Reachability.Gates;
+
+namespace StellaOps.Scanner.Reachability.Boundary;
+
+/// <summary>
+/// Context for boundary extraction, providing environment hints and detected gates.
+/// </summary>
+public sealed record BoundaryExtractionContext
+{
+    /// <summary>
+    /// Empty context for simple extractions.
+    /// </summary>
+    public static readonly BoundaryExtractionContext Empty = new();
+
+    /// <summary>
+    /// Environment identifier (e.g., "production", "staging").
+    /// </summary>
+    public string? EnvironmentId { get; init; }
+
+    /// <summary>
+    /// Deployment namespace or context (e.g., "default", "kube-system").
+    /// </summary>
+    public string? Namespace { get; init; }
+
+    /// <summary>
+    /// Additional annotations from deployment metadata.
+    /// </summary>
+    public IReadOnlyDictionary<string, string> Annotations { get; init; } = 
+        new Dictionary<string, string>();
+
+    /// <summary>
+    /// Gates detected by gate detection analysis.
+    /// </summary>
+    public IReadOnlyList<DetectedGate> DetectedGates { get; init; } = 
+        Array.Empty<DetectedGate>();
+
+    /// <summary>
+    /// Whether the service is known to be internet-facing.
+    /// </summary>
+    public bool? IsInternetFacing { get; init; }
+
+    /// <summary>
+    /// Network zone (e.g., "dmz", "internal", "trusted").
+    /// </summary>
+    public string? NetworkZone { get; init; }
+
+    /// <summary>
+    /// Known port bindings (port → protocol).
+    /// </summary>
+    public IReadOnlyDictionary<int, string> PortBindings { get; init; } =
+        new Dictionary<int, string>();
+
+    /// <summary>
+    /// Timestamp for the context (for cache invalidation).
+    /// </summary>
+    public DateTimeOffset Timestamp { get; init; } = DateTimeOffset.UtcNow;
+
+    /// <summary>
+    /// Source of this context (e.g., "k8s", "iac", "runtime").
+    /// </summary>
+    public string? Source { get; init; }
+
+    /// <summary>
+    /// Creates a context from detected gates.
+    /// </summary>
+    public static BoundaryExtractionContext FromGates(IReadOnlyList<DetectedGate> gates) =>
+        new() { DetectedGates = gates };
+
+    /// <summary>
+    /// Creates a context with environment hints.
+    /// </summary>
+    public static BoundaryExtractionContext ForEnvironment(
+        string environmentId,
+        bool? isInternetFacing = null,
+        string? networkZone = null) =>
+        new()
+        {
+            EnvironmentId = environmentId,
+            IsInternetFacing = isInternetFacing,
+            NetworkZone = networkZone
+        };
+}