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/advisory-detail.json

@@ -0,0 +1,20 @@
+{
+  "advisoryId": "CVE-2024-12345",
+  "source": "cve",
+  "title": "Example advisory for offline demo",
+  "severity": "high",
+  "publishedAt": "2025-12-01T00:00:00Z",
+  "updatedAt": "2025-12-10T00:00:00Z",
+  "cveIds": ["CVE-2024-12345"],
+  "affectedPurls": ["pkg:npm/example@1.2.3"],
+  "description": "Deterministic sample advisory payload for Console and SDK development.",
+  "references": [
+    {
+      "label": "Vendor bulletin",
+      "url": "https://example.invalid/advisories/CVE-2024-12345"
+    }
+  ],
+  "advisoryUrl": "https://example.invalid/advisories/CVE-2024-12345",
+  "etag": "\"adv-CVE-2024-12345-v1\""
+}
+