test: 17 new tests for S-4/5/6/7/9 integration tasks

S-4 Room hashing + ACL (8 tests in featherchat_compat.rs):
- hash_room_name: deterministic, 32 hex chars, different inputs differ
- hash_room_name_matches_fc_convention: manual SHA-256 verification
- room_acl: open mode, enforced mode, allow-listed, deny-unlisted

S-5 Handshake integration (4 tests in handshake_integration.rs):
- handshake_succeeds: real QUIC, encrypt/decrypt cross-verified
- handshake_verifies_identity: different seeds, session still works
- auth_then_handshake: AuthToken + CallOffer/Answer in sequence
- handshake_rejects_bad_signature: tampered sig → error

S-6/7/9 Web+Proto+TLS (5 tests in featherchat_compat.rs):
- auth_response_with_eth_address: FC's extra field handled
- wzp_proto_has_auth_token_variant: serialize/deserialize roundtrip
- all_fc_call_signal_types_representable: all 7 types verified
- hash_room_name_used_as_sni_is_valid: unicode/special chars → valid hex
- wzp_proto_cargo_toml_is_standalone: no workspace inheritance

196 total tests passing across all crates.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/wzp-relay/Cargo.toml

@@ -30,3 +30,6 @@ name = "wzp-relay"
 path = "src/main.rs"
 
 [dev-dependencies]
+tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }
+wzp-transport = { workspace = true }
+wzp-client = { workspace = true }