Add unit tests for Router configuration and transport layers

- Implemented tests for RouterConfig, RoutingOptions, StaticInstanceConfig, and RouterConfigOptions to ensure default values are set correctly.
- Added tests for RouterConfigProvider to validate configurations and ensure defaults are returned when no file is specified.
- Created tests for ConfigValidationResult to check success and error scenarios.
- Developed tests for ServiceCollectionExtensions to verify service registration for RouterConfig.
- Introduced UdpTransportTests to validate serialization, connection, request-response, and error handling in UDP transport.
- Added scripts for signing authority gaps and hashing DevPortal SDK snippets.

docs/governance/approvals-and-routing.md

@@ -0,0 +1,15 @@
+# Approvals & Routing (stub)
+
+> Status: BLOCKED — awaiting routing matrix, MFA rules, audit trail requirements (DOCS-EXC-25-002).
+
+## Outline
+1. Roles and approvers (matrix TBD)
+2. Routing rules per tenant/environment/resource
+3. MFA requirements and enforcement points
+4. Audit trail fields and retention
+5. Offline readiness (export/import of approvals)
+6. Verification steps (hash list + sample events)
+
+## Determinism
+- Add hashes to `docs/governance/SHA256SUMS` when populated.
+- Keep tables sorted by role/tenant/environment to minimize churn.