Add wire compatibility tests against captured 1.x traffic

Replay JSON-RPC messages recorded from ext-apps 1.7.x (sdk 1.x key
order and ids) through the 2.x App and AppBridge over a raw in-memory
transport and assert exactly what 2.x emits: the ui/initialize
handshake, params-less ui/notifications/initialized, tools/call in both
directions, and the -32002 to -32602 re-encoding on the host side. Also
check that AppBridge never sends an MCP initialize toward the View and
that the outer-client proxy works with a default (non-legacy) 2.x
Client/Server pair.