feat: add Reachability Center and Why Drawer components with tests

- Implemented ReachabilityCenterComponent for displaying asset reachability status with summary and filtering options.
- Added ReachabilityWhyDrawerComponent to show detailed reachability evidence and call paths.
- Created unit tests for both components to ensure functionality and correctness.
- Updated accessibility test results for the new components.

docs/api/gateway/samples/orchestrator-sources.json

@@ -0,0 +1,33 @@
+{
+  "items": [
+    {
+      "sourceId": "11111111-1111-1111-1111-111111111111",
+      "name": "concelier-ingest",
+      "sourceType": "concelier",
+      "enabled": true,
+      "paused": false,
+      "pauseReason": null,
+      "pauseTicket": null,
+      "createdAt": "2025-11-01T00:00:00Z",
+      "updatedAt": "2025-12-10T00:00:00Z",
+      "updatedBy": "user:demo"
+    },
+    {
+      "sourceId": "22222222-2222-2222-2222-222222222222",
+      "name": "export-center",
+      "sourceType": "export",
+      "enabled": true,
+      "paused": true,
+      "pauseReason": "Maintenance window",
+      "pauseTicket": "OPS-1234",
+      "createdAt": "2025-11-15T00:00:00Z",
+      "updatedAt": "2025-12-11T00:00:00Z",
+      "updatedBy": "user:ops"
+    }
+  ],
+  "count": 2,
+  "continuationToken": null,
+  "etag": "\"orch-sources-sample-1\"",
+  "traceId": "trace-sample-orch-1"
+}
+