* fix(subagents): apply tool policies to middleware-declared tools
* fix(subagents): address tool-policy review feedback
Normalize declaration conversion errors with middleware context, document
generated discovery exemptions, and add the Unreleased changelog entry.
Audit final explicit and middleware tool sets before graph creation, with
identity-based exemptions for generated discovery helpers and regressions.
* fix(subagents): reuse tool name resolution and clarify policy errors
