Parameters:
  scope: "canvas" (default) for jobs started from the current canvas,
         or "account" for every job on your account.
  tool:  optional filter, e.g. "covafold". Empty (default) returns EVERY
         durable job — an LLM asked "what jobs do I have?" must not be
         handed a silently truncated answer. A UI that can only act on one
         kind of job passes its own filter explicitly.

Returns: {jobs: [{job_id, tool, state, submitted_at, credits, importable}]}.
FREE — never costs credits. Never returns sequences or structures; fetch
those with covasyn_job_detail / covasyn_job_result.