ADR-021: third review round — tx-read methods, Job.claimed_at, schedule() queue validation, drop=rollback, receiver arms

docs/architecture/decisions/008-contract-v1-pinning.md

@@ -132,9 +132,13 @@ trait TxHandle {
     publish_with_key_tx(stream, key, payload) -> offset   // ADR-015
     notify_tx(channel, payload)
     save_offset_tx(stream, consumer, offset)
+    get_job_tx(queue, job_id) -> Option<Job>              // ADR-021
+    get_offset_tx(stream, consumer) -> i64                // ADR-021
+    read_since_tx(stream, offset, limit) -> Vec<StreamEvent>            // ADR-021
+    read_from_consumer_tx(stream, consumer, limit) -> Vec<StreamEvent>  // ADR-021
     outbox_enqueue_tx(outbox, opts, payload) -> job_id   // ADR-014
     commit(self: Box<Self>) -> Result<()>   // or rollback
-}
+}                                                                // ADR-021: drop = rollback
 ```
 
 *(Sketches elide `Result<>` wrappers on `*_tx` returns for brevity —