tests: Add jsonrpsee interoperability tests

Add integration tests that verify wire-format compatibility with jsonrpsee
when file descriptors are not present. Tests cover:

- Round-trip message exchange over Unix socket pairs
- Notification handling with proper synchronization
- Error response formatting per JSON-RPC 2.0 spec
- Sequential request handling
- Raw JSON parsing from external sources
- String and null ID handling
- Array params (positional parameters)

Also enable async-client feature for jsonrpsee and add async-trait
dev dependency.

Assisted-by: OpenCode (Sonnet 4)

Author: cgwalters

Cargo.toml

@@ -15,7 +15,8 @@ thiserror = "1.0"
 tokio = { version = "1.40", features = ["full"] }
 tracing = "0.1"
 tracing-subscriber = "0.3"
-jsonrpsee = { version = "0.24", features = ["server", "client-core"], default-features = false }
+jsonrpsee = { version = "0.24", features = ["server", "client-core", "async-client"], default-features = false }
 
 [dev-dependencies]
 tempfile = "3.0"
+async-trait = "0.1"