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).

tests/integration/test_preflight.py

@@ -94,14 +94,14 @@ def _seed_protocol_source(source):
 class TestProtocol:
     @pytest.mark.ci
     def test_protocol_current_version_accepted(self, shared_server):
-        """--protocol=2.26.0 (the current PROTOCOL_VERSION) is accepted and the
+        """--protocol=2.27.0 (the current PROTOCOL_VERSION) is accepted and the
         transfer completes normally."""
         source = os.path.join(TEST_DATA_DIR, "proto_ok_src")
         dest = os.path.join(TEST_DATA_DIR, "proto_ok_dst")
         shutil.rmtree(dest, ignore_errors=True)
         os.makedirs(dest)
         _seed_protocol_source(source)
-        result, _ = run_client(source, dest, flags=["--protocol=2.26.0"],
+        result, _ = run_client(source, dest, flags=["--protocol=2.27.0"],
                                port=shared_server.port)
         assert result.returncode == 0, \
             f"--protocol current run failed: {(result.stderr or result.stdout)[:400]}"