NapiServerHandler was bypassing IdentityProvider, calling
config.auth.authenticate_publickey() directly, which meant no Identity
was stored on the session and per-identity forwarding rules could not
match. It also skipped ForwardingPolicy::check() entirely, defeating
forwarding access control for NAPI-served tunnels. Both are now
consistent with ServerHandler and SshHandler behavior.
Review found Phase 1 approved with minor issues. Created cleanup tasks:
- napi-identity-provider-wiring (bug: NAPI bypasses IdentityProvider)
- panic-free-static-config (code smell: panic/unwrap in production path)
- non-exhaustive-public-api (future-proofing public API types)
- adr-doc-comments (doc convention: ADR references in new modules)
- ssh-session-recv-stub-doc (documentation: mark stubs as planned)
