Galaxy job errors aren't surfaced proactively in Orbit chat -- only when the user asks

A tool run that Galaxy immediately failed was not reported in the Orbit chat. From the user: "Galaxy UI immediately showed error but Orbit chatbox did not show error automatically. When I asked, then it could see there was an error."

What happens: `galaxy_run_tool` returns "Started tool ..." (HTTP 200 -- the job was submitted), and the agent treats that as success and moves on. The job then errors in Galaxy, but nothing polls the job to completion, so the failure is invisible until the user explicitly asks.

This is a trust problem -- a user watching only Orbit would believe the run succeeded. Expected: after submitting a job, surface terminal failures proactively (poll job/dataset state, or at least flag that submission != completion).

App 0.3.1, deepseek-v4-flash, trim_galore run. Overlaps the "don't claim completion before verifying artifacts" theme in #23 (this is the failure-surfacing flip side).

Start by locating the galaxy_run_tool implementation and tracing what happens after it returns the submission response; compare the behavior with the related completion-verification theme in #23. Reproduce the trim_galore failure against Galaxy and verify that terminal job or dataset failures are surfaced in Orbit chat without requiring the user to ask.

Written by the indexing model from the issue text.