Propagate ARAX's status code instead of dropping it

[maximusunc]

The ARAX worker logged the status code of the ARAX service's response and then threw it away: a non-2xx body was parsed and saved as if it were a TRAPI response, and anything that raised on the way (including .json() on an HTML error page) was swallowed into a non-TRAPI {"status": "error"} blob that the workflow reported as a successful query. Nothing downstream -- the span, the query's logs, the response the caller gets -- was left with a status code to report.

Failures now raise ARAXServiceError carrying ARAX's own status code, which puts it on the task span as arax.status_code, in the query's logs via run_task_lifecycle, and in a TRAPI response whose status/description say what happened; run_task_lifecycle then routes the query to finish_query with an ERROR status, matching the same fix already made in arax_pathfinder. Failures with no response at all -- connect errors and timeouts -- report 502 and 504 rather than a made-up code of their own.

Claude-Session: https://claude.ai/code/session_01BmsMzWR6tNbDM2uSxh47n8

[codecov]

Codecov Report

❌ Patch coverage is 90.19608% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.10%. Comparing base (541a94a) to head (58ae35f).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
workers/arax/worker.py	90.19%	3 Missing and 2 partials ⚠️

Files with missing lines	Coverage Δ
workers/arax/worker.py	76.19% <90.19%> (+76.19%)	⬆️

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