Ack duplicate Codex interrupts after completion

[danshapiro]

Summary

• track completed Codex turn ids in the remote proxy
• locally acknowledge duplicate turn/interrupt requests for already completed turns instead of forwarding them upstream
• add a regression test for repeated Esc after turn completion

Root cause

Logs showed the first Esc sent turn/interrupt id 6, which received an upstream response and was immediately followed by thread/status/changed and turn/completed for the same turn. A repeated Esc then sent turn/interrupt id 7 after completion, and no upstream response was logged. The proxy recorded pending request ids but did not use turn/completed evidence, so that duplicate request could leave the TUI waiting forever.

Test plan

• npm run test:vitest -- run test/unit/server/coding-cli/codex-app-server/remote-proxy.test.ts --testNamePattern "acks duplicate turn/interrupt"
• npm run test:vitest -- run test/unit/server/coding-cli/codex-app-server/remote-proxy.test.ts
• FRESHELL_TEST_SUMMARY="codex duplicate interrupt freeze fix" npm run check