feat: Add PathViewer and RiskDriftCard components with templates and styles

- Implemented PathViewerComponent for visualizing reachability call paths.
- Added RiskDriftCardComponent to display reachability drift results.
- Created corresponding HTML templates and SCSS styles for both components.
- Introduced test fixtures for reachability analysis in JSON format.
- Enhanced user interaction with collapsible and expandable features in PathViewer.
- Included risk trend visualization and summary metrics in RiskDriftCard.

src/Scanner/__Tests/StellaOps.Scanner.Reachability.Tests/Fixtures/graph-with-runtime.golden.json

@@ -0,0 +1,45 @@
+{
+  "_type": "https://in-toto.io/Statement/v1",
+  "subject": [
+    {
+      "name": "pkg:oci/production-app@sha256:xyz789",
+      "digest": {
+        "sha256": "xyz789abc123def456789012345678901234567890123456789012345678"
+      }
+    }
+  ],
+  "predicateType": "https://stellaops.io/attestation/reachabilityWitness/v1",
+  "predicate": {
+    "version": "1.0.0",
+    "analysisTimestamp": "2025-01-15T12:30:00.0000000Z",
+    "analyzer": {
+      "name": "stellaops.scanner.reachability",
+      "version": "1.0.0"
+    },
+    "graph": {
+      "schema": "richgraph-v1",
+      "hash": "blake3:fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210",
+      "nodeCount": 150,
+      "edgeCount": 340,
+      "casUri": "cas://reachability/graphs/fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210"
+    },
+    "summary": {
+      "sinkCount": 12,
+      "entrypointCount": 8,
+      "pathCount": 45,
+      "gateCoverage": 0.67
+    },
+    "policy": {
+      "hash": "sha256:policy123456789012345678901234567890123456789012345678901234"
+    },
+    "source": {
+      "commit": "a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2"
+    },
+    "runtime": {
+      "observedAt": "2025-01-15T12:25:00.0000000Z",
+      "traceCount": 1250,
+      "coveredPaths": 38,
+      "runtimeConfidence": 0.84
+    }
+  }
+}