Define an Oban worker that runs a claude job.

A worker is a task definition; a job is one instance of it. The claude args are a merge of worker-level defaults (:args) and the per-job args, the job winning on conflicts. That spans a spectrum from one mechanism:

• no defaults -> the job carries everything (a bare Oban-to-claude passthrough)
• fixed config in the worker, the variable input in the job (the common case)
• everything in the worker, an empty job -> a routine, e.g. scheduled with Oban.Plugins.Cron

Example

defmodule MyApp.PrReview do
  use ObanClaude.Worker,
    queue: :review,
    max_attempts: 3,
    args: ObanClaude.Args.defaults(model: "sonnet", system_prompt: "Review the pull request.")

  @impl ObanClaude.Worker
  def handle_result(result, _job) do
    case ObanClaude.outcome(result) do
      "blocked" -> {:cancel, :blocked}
      _ -> :ok
    end
  end
end

# the job is just the instance:
MyApp.PrReview.new(ObanClaude.Args.new(prompt: "PR #4321: " <> diff))
|> Oban.insert()

use ObanClaude.Worker accepts every Oban.Worker option (:queue, :max_attempts, :unique, :priority, ...) plus:

• :args -- a map of default claude args, merged under each job's args (the job wins). Defaults to %{}. Build it with ObanClaude.Args.defaults/1 (prompt-optional; evaluates at compile time) or write the string map directly. It may reference module attributes defined before use.
• :classifier -- the outcome -> Oban-return mapping (see ObanClaude.Outcome), forwarded to ObanClaude.run/2.
• :query_fun -- the claude entrypoint (defaults to &ClaudeWrapper.query/2), forwarded to ObanClaude.run/2; override to stub claude in tests.

It injects a perform/1 that merges the worker defaults under the job args, runs ObanClaude.run/2, calls handle_result/2 on success, and passes a claude-level {:error,...} / {:cancel,...} / {:snooze,...} straight through to Oban. Both perform/1 and handle_result/2 are overridable.