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/delete_plan.h

@@ -84,7 +84,7 @@ size_t delete_plan_session_deleted(const DeletePlanSession* 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);
+void delete_plan_session_set_delete_observer(DeletePlanSession* session,
+                                             DeletePathObserver observer, void* context);
 
 #endif