Add signal contracts for reachability, exploitability, trust, and unknown symbols

- Introduced `ReachabilityState`, `RuntimeHit`, `ExploitabilitySignal`, `ReachabilitySignal`, `SignalEnvelope`, `SignalType`, `TrustSignal`, and `UnknownSymbolSignal` records to define various signal types and their properties.
- Implemented JSON serialization attributes for proper data interchange.
- Created project files for the new signal contracts library and corresponding test projects.
- Added deterministic test fixtures for micro-interaction testing.
- Included cryptographic keys for secure operations with cosign.

docs/api/console/samples/console-run-stream-sample.ndjson

@@ -0,0 +1,7 @@
+{"runId":"run::2025-12-04::7f3a2e91","kind":"queued","message":"Run queued for processing.","updatedAt":"2025-12-04T11:55:00Z"}
+{"runId":"run::2025-12-04::7f3a2e91","kind":"started","message":"Run started, initializing scanner.","updatedAt":"2025-12-04T11:55:12Z"}
+{"runId":"run::2025-12-04::7f3a2e91","kind":"progress","progressPercent":25,"message":"Scanning layer 1/4.","updatedAt":"2025-12-04T11:56:01Z"}
+{"runId":"run::2025-12-04::7f3a2e91","kind":"progress","progressPercent":50,"message":"Scanning layer 2/4.","updatedAt":"2025-12-04T11:56:45Z"}
+{"runId":"run::2025-12-04::7f3a2e91","kind":"progress","progressPercent":75,"message":"Scanning layer 3/4.","updatedAt":"2025-12-04T11:57:28Z"}
+{"runId":"run::2025-12-04::7f3a2e91","kind":"progress","progressPercent":100,"message":"Finalizing SBOM generation.","updatedAt":"2025-12-04T11:58:10Z"}
+{"runId":"run::2025-12-04::7f3a2e91","kind":"completed","progressPercent":100,"message":"Run completed successfully. Found 12 vulnerabilities.","updatedAt":"2025-12-04T11:58:22Z"}

docs/api/console/samples/console-status-sample.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "https://stella-ops.org/api/console/console-status.schema.json",
+  "_meta": {
+    "description": "Sample response for GET /console/status",
+    "task": "WEB-CONSOLE-23-002",
+    "generatedAt": "2025-12-04T12:00:00Z"
+  },
+  "backlog": 12,
+  "queueLagMs": 245,
+  "activeRuns": 3,
+  "pendingRuns": 5,
+  "lastCompletedRunId": "run::2025-12-04::7f3a2e91",
+  "lastCompletedAt": "2025-12-04T11:58:22Z",
+  "healthy": true
+}