feat(parity): real --info=del deletion lines + rsync throttle pacing

- Wire: config frame gains report_deletes (protocol 2.26.0 -> 2.27.0); the
  receiver lists actually-removed paths in the STATUS_STATS path list, so the
  sender prints rsync's `deleting PATH` / `*deleting   PATH` lines for a real
  --delete run (and -i/out-format).  Observers threaded through the manifest,
  missing-args and per-directory delete engines; golden wire len/hash updated.
- bwlimit: throttle now paces like rsync 3.4.1 -- ~100ms burst capacity and the
  sleep is no longer credited as refill, so 4 MiB at 1024/2048 KiB/s matches
  rsync within ~4% (was ~2x too fast).

src/shared/delete_plan.h

@@ -5,6 +5,7 @@
 #include "config.h"
 #include "file_receive.h"
 #include "protocol.h"
+#include "utils.h"
 #include <stdbool.h>
 
 /* Per-directory delete plans (protocol 2.24.0).
@@ -79,5 +80,11 @@ bool delete_plan_session_limit_reached(const DeletePlanSession* session);
 /* Number of destination entries the session's plans removed (or, for
    --delete-delay, snapshotted for removal), for the end-of-transfer stats. */
 size_t delete_plan_session_deleted(const DeletePlanSession* session);
+/* Install an observer invoked for every destination-relative path the session
+   truly removes (including the deferred --delete-delay commit), so the receiver
+   can report rsync's `deleting PATH` lines through the terminal STATUS_STATS
+   record.  Pass NULL/0 to clear. */
+void delete_plan_session_set_delete_observer(DeletePlanSession* session, DeletePathObserver observer,
+                                             void* context);
 
 #endif