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/modules/cli/guides/exceptions.md

@@ -0,0 +1,11 @@
+# CLI Exceptions Guide (stub)
+
+> Status: BLOCKED — depends on exception API contract and CLI command shapes (DOCS-EXC-25-006). Outline fixed to reduce future churn.
+
+## Outline
+- Imposed rule banner
+- Commands: list, get, create, approve, reject (actual names TBD)
+- Flags/exit codes (to be filled when CLI contract arrives)
+- Examples with deterministic outputs (hash in `docs/modules/cli/guides/SHA256SUMS` when available)
+- Offline/air-gap usage notes
+- Troubleshooting and known errors