[YIELD-2] tcp-outbound/write/drop Worker 연동 + fl-yield 구현
완료보통
🤖 claude
tcp-outbound: postMessage({cmd:connect,id,host,port,handler})로 Worker에 위임. tcp-write: upstream이면 Worker postMessage. fl-yield(ms): Atomics.wait(ctrl,2,0,ms) → readPos~writePos 드레인 → callFnVal. 빌드 목표: npm run build.