feat(stats): receiver-observed created/literal counters (protocol 2.28.0)

- PROTOCOL_VERSION 2.27.0 -> 2.28.0; STATUS_STATS gains literal_bytes and
  the created reg/dir/link/special counters (golden wire updated)
- receiver reports which destination entries it newly created, including
  implicitly-created parent directories below the logical transfer root, so
  Number of created files carries rsync's per-type breakdown
- Literal data is now exact for a delta transfer (receiver counts the literal
  fragments it stored)
- differential-tested vs rsync 3.4.1 for fresh-create, update and delta

src/shared/file.h

@@ -87,6 +87,11 @@ bool file_path_exists_secure(const char* path);
 bool file_stat_secure(const char* path, struct stat* st);
 bool file_destination_is_newer_secure(const char* path, const FileMetadata* metadata);
 int file_open_secure_parent(const char* path, char** leaf_out, bool create_dirs);
+/* Protocol 2.28.0 variant: also increments *dirs_created for every missing
+ * parent directory this walk creates that lies strictly below `count_floor`
+ * (a receive-root-relative path, or NULL to count all of them). */
+int file_open_secure_parent_counted(const char* path, char** leaf_out, bool create_dirs,
+                                    unsigned* dirs_created, const char* count_floor);
 bool file_ensure_directory_secure(const char* path);
 bool file_directory_exists_secure(const char* path);
 bool file_rename_secure(const char* old_path, const char* new_path);
@@ -158,5 +163,27 @@ bool file_to_disk_secure_link_attrs(const char* path, const char* basis_path, co
                                     const FileMetadata* metadata, FileAttrPolicy policy,
                                     bool use_fsync, const FileXattrList* xattrs, bool fake_super,
                                     const char* temp_dir);
+/* Protocol 2.28.0 receiver-stat variants: like the two above but additionally
+ * report through `dirs_created` (when non-NULL) how many parent directories the
+ * confined secure walk had to create that lie strictly below `count_floor` (a
+ * receive-root-relative prefix, or NULL for all).  Used to reproduce rsync's
+ * `Number of created files` directory count on a fresh destination. */
+bool file_to_disk_secure_attrs_counted(const char* path, const void* data,
+                                       unsigned long long data_size, bool inplace, bool sparse,
+                                       bool preallocate, const FileMetadata* metadata,
+                                       FileAttrPolicy policy, bool update, bool no_replace,
+                                       bool use_fsync, const FileXattrList* xattrs, bool fake_super,
+                                       bool keep_partial, const char* temp_dir,
+                                       unsigned* dirs_created, const char* count_floor);
+bool file_to_disk_secure_link_attrs_counted(const char* path, const char* basis_path,
+                                            const void* data, unsigned long long data_size,
+                                            bool preallocate, const FileMetadata* metadata,
+                                            FileAttrPolicy policy, bool use_fsync,
+                                            const FileXattrList* xattrs, bool fake_super,
+                                            const char* temp_dir, unsigned* dirs_created,
+                                            const char* count_floor);
+/* The logical transfer root expressed receive-root-relative, or NULL when the
+ * wire paths carry no mirror scaffolding above it.  Caller frees non-NULL. */
+char* file_transfer_root_floor(const Config* config);
 
 #endif