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/utils.h

@@ -134,6 +134,19 @@ bool path_under_skip_prefix(const char* child_rel, bool at_root, const DeleteSki
    cap and returns DELETE_WALK_LIMIT_REACHED when more extras remained.
    `deleted_out`/`skipped_out` optionally receive the number of entries removed
    and the number skipped because of the cap. */
+/* Optional per-deletion observer: called for each destination-relative path
+   actually removed (a file, symlink, or directory), in removal order, so the
+   receiver can stream rsync's `--info=del`/`--info=remove` lines. */
+typedef void (*DeletePathObserver)(void* context, const char* rel_path);
+
+/* `delete_extras_limited_observed` is delete_extras_limited with an optional
+   observer; the observer is invoked only for entries truly removed. */
+DeleteWalkResult delete_extras_limited_observed(const char* dest_root, const ArrayList* manifest,
+                                                const ArrayList* synced_dirs, size_t max_delete,
+                                                const DeleteSkipEntry* skips, int skip_count,
+                                                size_t* deleted_out, size_t* skipped_out,
+                                                DeletePathObserver observer, void* observer_context);
+
 DeleteWalkResult delete_extras_limited(const char* dest_root, const ArrayList* manifest,
                                        const ArrayList* synced_dirs, size_t max_delete,
                                        const DeleteSkipEntry* skips, int skip_count,