fix(delete): match rsync deletion semantics (#290)

- Scope the --delete extras walk to directories synchronized by the
  transfer: add a synchronized-directory section to the delete manifest
  (protocol 2.23.0) so --files-from subsets no longer delete untransmitted
  paths outside listed directory subtrees (data-loss fix).
- Separate --max-size/--min-size prune protection from --delete-excluded so
  size-pruned source mirrors survive (rsync parity).
- Unlink extraneous destination symlinks instead of skipping them.
- Make --max-delete partial (delete up to N, skip the rest) and exit 25;
  accept negative values as unlimited.
- Draw --delete-missing-args deletions from the shared --max-delete budget.
- Honor --force during --delay-updates publication.

Add unit and integration regression tests; update the pinned config wire
golden and version strings for the 2.23.0 manifest/status additions.

src/shared/multiprocessing.h

@@ -42,6 +42,18 @@ typedef struct {
      scanner's exclusion sink) or, in the early modes, by the path-only pre-scan
      on the calling thread before the pipeline starts. */
   ArrayList* excluded_paths;
+  /* --max-size/--min-size pruned source paths.  These are ALWAYS sent as
+     protected prefixes (even with --delete-excluded), so the destination
+     mirrors of size-skipped files survive --delete like rsync.  Populated by
+     the scanner thread (workers append under mutex_scanner) or, in the early
+     modes, by the path-only pre-scan on the calling thread. */
+  ArrayList* size_skipped_paths;
+  /* Destination-relative paths of the directories the source scan synchronized
+     for this run (the receive root is the "." sentinel).  Sent with the
+     manifest so the receiver confines its extras walk to them, matching rsync's
+     "delete only in synchronized directories" (notably for --files-from).
+     Populated by the scanner thread or the early pre-scan. */
+  ArrayList* synced_dirs;
   /* --delete-missing-args: the destination-relative mirrors of the --files-from
      entries that are missing under the source.  Computed by the preflight on
      the calling thread before the pipeline starts; the sender thread transmits
@@ -83,6 +95,10 @@ typedef struct {
   ArrayList* dir_entries;
   mtx_t dir_entries_mutex;
   bool dir_entries_mutex_init;
+  /* Set by the sender thread when the receiver reported a --max-delete-capped
+     deletion (STATUS_DELETE_LIMIT): the transfer succeeded and the process must
+     exit 25 like rsync.  Read by the caller after the sender thread is joined. */
+  bool delete_limit;
 } PipelineContextSender;
 
 /* `config` is borrowed and must outlive the context: destroy does NOT free it,