test(parity): option-wave rsync differentials + docs (109/21/26)

- tests/integration/test_option_parity.py: bwlimit parse matrix + throttle
  rate, --info flist/name/nonreg/del(dry+real+itemize)/remove, real-setpriv
  --ignore-errors, rsync-daemon -M forwarding evidence, filter protect/risk
  destination-only divergence pin.
- RSYNC_COMPAT.md: tally 109/21/26; --bwlimit and --ignore-errors -> Parity,
  --filter and -M -> Divergent with differential rationale, --info residual
  narrowed to the categories with no client-observable event.
- HANDOFF/README: protocol 2.27.0, option-wave summary.

src/shared/file_receive.h

@@ -132,7 +132,8 @@ bool manifest_delete_missing_args_limited(const Config* config, DeleteManifest*
 bool manifest_delete_missing_args_limited_observed(const Config* config, DeleteManifest* manifest,
                                                    size_t max_delete, size_t* deleted,
                                                    size_t* skipped, bool* limit_hit,
-                                                   DeletePathObserver observer, void* observer_context);
+                                                   DeletePathObserver observer,
+                                                   void* observer_context);
 /* Outcome of committing a delete manifest.  LIMIT_REACHED reports rsync's
    partial --max-delete result: the budget allowed some deletions and the rest
    were skipped (the run still stores all file data but the client exits 25). */