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/db/schemas/audit.sql

@@ -0,0 +1,23 @@
+-- Shared audit schema (generic event log usable by multiple modules)
+-- Status: PROPOSED (2025-12-05)
+
+CREATE SCHEMA IF NOT EXISTS audit;
+
+CREATE TABLE IF NOT EXISTS audit.events (
+    id BIGSERIAL PRIMARY KEY,
+    tenant_id UUID NOT NULL,
+    module TEXT NOT NULL,                 -- e.g., authority, scheduler, notify, issuer
+    entity_type TEXT NOT NULL,            -- e.g., issuer, schedule, policy_pack
+    entity_id UUID,
+    action TEXT NOT NULL,                 -- e.g., create, update, delete
+    actor TEXT,
+    actor_type TEXT CHECK (actor_type IN ('user','service','system')),
+    reason TEXT,
+    details JSONB DEFAULT '{}'::jsonb,
+    correlation_id TEXT,
+    occurred_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_audit_module_time ON audit.events(module, occurred_at DESC);
+CREATE INDEX IF NOT EXISTS idx_audit_tenant_time ON audit.events(tenant_id, occurred_at DESC);
+CREATE INDEX IF NOT EXISTS idx_audit_entity ON audit.events(entity_type, entity_id);