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/config.h

@@ -259,9 +259,17 @@ typedef enum SuperMode { SUPER_MODE_AUTO = 0, SUPER_MODE_ON = 1, SUPER_MODE_OFF
  * for -n/--dry-run --delete, the destination-relative paths it WOULD have
  * deleted.  It is set by the client only when --stats, --progress/-P, an
  * --out-format token needs a wire counter (%b/%c), or a dry-run carries
+ * --delete; the transfer decision itself is unchanged.
+ *
+ * --info wave (protocol 2.27.0).  report_deletes tells the receiver to include
+ * the destination-relative paths it ACTUALLY removed in its terminal
+ * STATUS_STATS record (the same path-list field the dry-run would-delete report
+ * uses), so the sender can print rsync's `deleting PATH`/`*deleting` lines for a
+ * real (non-dry-run) deletion.  It is set only when --info=del is requested with
  * --delete; the transfer decision itself is unchanged. */
 #define CONFIG_WIRE_OUTPUT_FIELDS(X)                                                               \
-  X(report_dest_info, bool, false, BOOL) X(report_stats, bool, false, BOOL)
+  X(report_dest_info, bool, false, BOOL) X(report_stats, bool, false, BOOL)                        \
+      X(report_deletes, bool, false, BOOL)
 
 /* Codec-negotiation wave (protocol 2.26.0).  compression_algo is the concrete
  * codec the client selected for this transfer (a CompressionAlgo id) and is the
@@ -988,7 +996,14 @@ typedef struct Config {
  * boundary, and the strict same-version handshake (config_receive rejects a
  * mismatched version before parsing anything else) keeps mixed deployments from
  * ever reaching that state. */
-#define PROTOCOL_VERSION "2.26.0"
+/* (7) --info=del report (protocol 2.27.0): the config frame gains one trailing
+ * bool, report_deletes, appended after report_stats.  When set, the receiver
+ * lists the paths it actually removed in the terminal STATUS_STATS path list
+ * (the same count-delimited list the -n/--dry-run would-delete report uses), so
+ * the sender can print rsync's `deleting PATH` lines for a real deletion.  No
+ * change to the fixed STATUS_STATS record itself; only a new trailing config
+ * bool, which still requires the version bump for the strict lockstep. */
+#define PROTOCOL_VERSION "2.27.0"
 #define DEFAULT_CHUNK_SIZE (10 * 1024 * 1024)
 /* Upper bound on total basis-dir entries (rsync caps --link-dest at 20). */
 #define MAX_BASIS_DIRS 64