feat: Add Scanner CI runner and related artifacts

- Implemented `run-scanner-ci.sh` to build and run tests for the Scanner solution with a warmed NuGet cache.
- Created `excititor-vex-traces.json` dashboard for monitoring Excititor VEX observations.
- Added Docker Compose configuration for the OTLP span sink in `docker-compose.spansink.yml`.
- Configured OpenTelemetry collector in `otel-spansink.yaml` to receive and process traces.
- Developed `run-spansink.sh` script to run the OTLP span sink for Excititor traces.
- Introduced `FileSystemRiskBundleObjectStore` for storing risk bundle artifacts in the filesystem.
- Built `RiskBundleBuilder` for creating risk bundles with associated metadata and providers.
- Established `RiskBundleJob` to execute the risk bundle creation and storage process.
- Defined models for risk bundle inputs, entries, and manifests in `RiskBundleModels.cs`.
- Implemented signing functionality for risk bundle manifests with `HmacRiskBundleManifestSigner`.
- Created unit tests for `RiskBundleBuilder`, `RiskBundleJob`, and signing functionality to ensure correctness.
- Added filesystem artifact reader tests to validate manifest parsing and artifact listing.
- Included test manifests for egress scenarios in the task runner tests.
- Developed timeline query service tests to verify tenant and event ID handling.

docs/modules/platform/AGENTS.md

@@ -8,6 +8,7 @@ Platform module describes cross-cutting architecture, contracts, and guardrails
 - [Architecture](./architecture.md)
 - [Implementation plan](./implementation_plan.md)
 - [Task board](./TASKS.md)
+- [Architecture overview](./architecture-overview.md)
 
 ## How to get started
 1. Open sprint file `/docs/implplan/SPRINT_*.md` and locate the stories referencing this module.