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/exceptions.md

@@ -0,0 +1,24 @@
+# Exception Governance (stub)
+
+> Status: BLOCKED — awaiting lifecycle/routing matrix and API contract from Governance/Authority/Platform guilds. This stub sets structure and determinism requirements for DOCS-EXC-25-001.
+
+## Scope
+- Exception lifecycle, scope patterns, compliance checklist.
+- Deterministic artifacts for offline/air-gap use.
+
+## Pending inputs
+- Final lifecycle states and transitions.
+- Scope pattern examples (tenant/env/service/resource).
+- Compliance checklist from Governance Guild.
+
+## Outline
+1. Imposed rule banner (to be filled)
+2. Exception lifecycle (states, transitions, allowed actors)
+3. Scope patterns and examples
+4. Compliance checklist
+5. Offline/air-gap packaging notes
+6. Verification (hash + replay of fixtures)
+
+## Determinism
+- When content is added, record hashes in `docs/governance/SHA256SUMS`.
+- Use UTC timestamps and stable ordering of tables.