feat(14-02): conga.Describe reports a registered job's kind, queue, attempts and timeout

- lets a plugin test assert what its Jobs() registers, such as the CSV
  match job's 240 s timeout, without reaching into conga internals
- README API table, jobs docs page and an example

modules/conga/job.go

@@ -107,6 +107,27 @@ func (w *riverWorker[T]) Timeout(*river.Job[T]) time.Duration {
 	return w.job.cfg.timeout
 }
 
+// JobInfo describes a job built by Job: its kind and the defaults its
+// options set (zero values mean the queue config defaults apply).
+type JobInfo struct {
+	Kind        string
+	Queue       string
+	MaxAttempts int
+	Timeout     time.Duration
+}
+
+// Describe returns the kind and option defaults of a job built by Job, so
+// a plugin's tests can assert what Jobs() registers (for example a job's
+// Timeout). ok is false for a pact.Job that was not built by Job.
+func Describe(j pact.Job) (info JobInfo, ok bool) {
+	cj, ok := j.(congaJob)
+	if !ok || cj == nil {
+		return JobInfo{}, false
+	}
+	cfg := cj.config()
+	return JobInfo{Kind: cj.kind(), Queue: cfg.queue, MaxAttempts: cfg.maxAttempts, Timeout: cfg.timeout}, true
+}
+
 type jobIDKey struct{}
 
 // JobID returns the summer_jobs id of the dispatched job running in ctx.