fix(parity): rsync bwlimit units, --info categories, --ignore-errors deletion semantics

- --bwlimit: faithful port of rsync 3.4.1 parse_size_arg (default KiB/s,
  binary K/M/G/T/P, decimal KB/MB, KiB/MiB, decimals, 0 = unlimited, 512-byte
  floor, (size+512)/1024 quantization).  Unit tests + docs.
- --info: wire del/remove/name/flist/nonreg/progress to real FastSync events in
  rsync's line format (deleting PATH, sender removed NAME, name lines,
  'sending incremental file list', skipping non-regular file "NAME"); name no
  longer aliases copy; --info=progress drives the progress path and report_stats.
- --ignore-errors: match rsync's default -- a source I/O error skips deletion
  unless --ignore-errors, while the readable tree still transfers and the run
  exits 23.  Covers all delete timings and both send paths.

src/client/scanner.h

@@ -121,9 +121,18 @@ typedef struct {
    * it) and to emit its plan after the data stream, when no file frame would
    * otherwise trigger it.  Guarded by `excluded_mutex`. */
   ArrayList* plan_dirs;
-  /* --ignore-errors: an unreadable directory during the scan is recorded as an
-   * I/O error and skipped instead of aborting the scan.  Client-only. */
+  /* --ignore-errors: an unreadable subdirectory no longer aborts the scan (it
+   * is always skipped so the rest of the tree transfers); this flag is kept so
+   * the client can distinguish the option state when deciding deletion policy.
+   * Client-only. */
   bool ignore_io_errors;
+  /* --info=nonreg: print rsync's `skipping non-regular file "NAME"` line for a
+   * non-regular entry that is not being preserved.  Client-only. */
+  bool note_nonreg;
+  /* Source root and 8-bit-output policy used to render a `--info=nonreg` name
+   * relative to the transfer root.  Borrowed read-only. */
+  const char* send_directory;
+  bool eight_bit_output;
   /* --ignore-missing-args (implied by --delete-missing-args): an explicitly
    * --files-from-listed entry that does not exist under the source is skipped
    * instead of failing (the --dirs generator is the only scanner path that
@@ -186,6 +195,10 @@ typedef struct {
      --ignore-errors the scan continues past it and the caller decides what to
      do; `failed` is reserved for fatal errors that always abort the scan. */
   bool io_error;
+  /* The transfer ROOT could not be opened.  It is always fatal, even under
+     --ignore-errors, but the client still maps it to rsync's partial-transfer
+     exit (23) rather than a generic failure. */
+  bool root_io_error;
 } DirectoryScanner;
 
 typedef struct {
@@ -206,6 +219,7 @@ typedef struct {
   Chunk* initial_chunk;
   ProtocolSession* allocation_session;
   FilterNode* root_filter_node; /* root .rsync-filter context (owned by ps) */
+  const ScannerOptions* options; /* borrowed scan options (--info=nonreg output) */
 } ParallelScanner;
 
 DirectoryScanner* directory_scanner_create(const char* root_directory, bool use_metadata,