refactor(acp): extract NdjsonRpcTransport from acp-lifecycle-probe.ts (#4235 step 2)

Extract NdjsonRpcTransport class (1022 lines) from acp-lifecycle-probe.ts into acp-lifecycle/ndjson-rpc-transport.ts. Probe file drops by ~900 lines. Backward-compatible re-exports maintained. Boss override: cohesive extraction, not god file.

Author: OneStepAt4time