Handle live stream quota errors

[codemountains]

Summary

• recognize the private live-stream concurrency and daily-quota API errors
• keep rejected stream output off JSONL stdout while adding actionable stderr guidance
• display the daily quota UTC reset message and numeric Retry-After delay
• document admission rejection and reconnect termination behavior

Why

The backend now enforces free-service live-stream cost controls. The CLI
previously surfaced only the backend message and did not recognize the new
error codes or preserve the Retry-After response header for presentation.

User and developer impact

Concurrency rejection now advises users to close another live stream. Daily
quota rejection shows both the backend-provided UTC reset time and the retry
delay. Initial 429 admission failures leave stdout empty and exit non-zero
without reconnecting. If a clean EOF is followed by a quota 429, the CLI stops
after that reconnect response instead of entering another reconnect cycle.

Validation

• TDD red: 3 focused stream-quota tests failed before implementation
• focused test: 1 file / 12 tests passed
• just check: 29 files / 230 tests passed, with typecheck and lint
• just package: npm package smoke test passed
• just ci: 29 files / 230 tests passed with coverage and repository checks
• git diff --check

Related issues

• Closes [Feature]: Handle live stream concurrency and daily quota errors #3