Enhance risk API documentation and error handling

- Updated API documentation for risk endpoints to include optional caching headers and error catalog references.
- Added a new error catalog JSON file to standardize error responses.
- Improved explainability documentation with sample outputs for console and CLI.
- Added SHA256 checksums for new sample files related to explainability.
- Refined AocGuard tests to utilize a helper method for generating test JSON, improving readability and maintainability.
- Updated runbook references to ensure consistency in sprint documentation.
- Introduced stub implementations for MongoDB storage interfaces and options, laying groundwork for future development.
- Disabled analytics in Angular CLI configuration for privacy considerations.

docs/risk/samples/explain/console-frame.json

@@ -0,0 +1,19 @@
+{
+  "frame_id": "console-explain-001",
+  "captured_at": "2025-12-05T00:05:00Z",
+  "finding_id": "finding-123",
+  "profile_id": "default-profile",
+  "score": 0.85,
+  "severity": "high",
+  "gates": ["kev_and_reachability"],
+  "top_contributors": [
+    {"factor": "cvss", "contribution": 0.4, "raw": 7.5, "provenance": "sha256:cvsshash"},
+    {"factor": "kev", "contribution": 0.3, "raw": true, "provenance": "sha256:kevhash"},
+    {"factor": "reachability", "contribution": 0.3, "raw": 0.9, "provenance": "sha256:reachhash"}
+  ],
+  "provenance": {"job_hash": "sha256:jobhash"},
+  "charts": {
+    "donut": {"high": 1},
+    "stacked": [0.4, 0.3, 0.3]
+  }
+}