feat: Add UI benchmark driver and scenarios for graph interactions

- Introduced `ui_bench_driver.mjs` to read scenarios and fixture manifest, generating a deterministic run plan.
- Created `ui_bench_plan.md` outlining the purpose, scope, and next steps for the benchmark.
- Added `ui_bench_scenarios.json` containing various scenarios for graph UI interactions.
- Implemented tests for CLI commands, ensuring bundle verification and telemetry defaults.
- Developed schemas for orchestrator components, including replay manifests and event envelopes.
- Added mock API for risk management, including listing and statistics functionalities.
- Implemented models for risk profiles and query options to support the new API.

docs/modules/signals/heuristics/heuristics.schema.json

@@ -0,0 +1,32 @@
+{
+  "$id": "https://stella-ops.org/schemas/heuristics.schema.json",
+  "type": "object",
+  "required": ["version", "updatedAt", "heuristics", "signing"],
+  "properties": {
+    "version": {"type": "string"},
+    "updatedAt": {"type": "string", "format": "date-time"},
+    "heuristics": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "required": ["id", "band", "inputs", "formula", "normalization"],
+        "properties": {
+          "id": {"type": "string"},
+          "band": {"enum": ["gold", "silver", "bronze"]},
+          "inputs": {"type": "array", "items": {"type": "string"}},
+          "formula": {"type": "string"},
+          "normalization": {"type": "string"},
+          "evidence": {"type": "array", "items": {"type": "string"}}
+        }
+      }
+    },
+    "signing": {
+      "type": "object",
+      "required": ["predicate", "dsse_required"],
+      "properties": {
+        "predicate": {"type": "string"},
+        "dsse_required": {"type": "boolean"}
+      }
+    }
+  }
+}