Rate-Limit Detection, Job Retry, and Tool-Continuation Fix

Features

• Rate-limit detection: the Claude CLI worker detects when the Claude Code CLI hits a usage limit or quota cap and reports rate_limit_status, rate_limit_type, and estimated retry_after_secs to the server via a job.overload message.
• Provider usage snapshot: rate-limit fields are persisted to the provider usage snapshot so the server dashboard can surface a warning and reset time immediately without polling.
• Automatic job retry on rate limit: jobs that hit a rate limit are re-queued on the work coordinator rather than permanently failed, and re-dispatched once the backoff window elapses.

Fixes

• Fixed tool-continuation flow: the stdin pipe is now correctly closed after writing the tool result, preventing the Claude CLI from hanging while waiting for more input.