feat: add --files-from/-0, --filter, -C and -F filter layer

Implement the RSYNC_COMPAT Phase-2 filter/parser feature group:
- --files-from=FILE (repeatable) plus -0/--from0 NUL delimiters: parse the
  source file list relative to the source root into a shared read-only
  allow-set; the scanner transfers listed files and the whole subtree of
  listed directories and prunes everything else in single- and
  multithreaded mode. Absolute/'..' entries and missing files are hard
  CLI errors.
- --filter=RULE: rsync-style +/- rules (anchored '/', dir-only trailing '/',
  word include/exclude forms) evaluated first-match-wins with a default of
  include, as an independent layer from legacy --exclude/--include.
  Unsupported directives (merge/hide/... ) are rejected explicitly. -f stays
  sendfile.
- -C/--cvs-exclude: well-known rsync CVS default exclude set.
- -F: per-directory .rsync-filter files read during traversal and applied to
  the owning directory's subtree (single + parallel), never transferred.
- Delete manifest still derives from what was actually sent.

Client-only config fields; no wire/protocol change. Adds unit coverage
(CLI parse, allow-set and filter scanning single+parallel) and integration
tests (TestFilesFrom, TestFilters). RSYNC_COMPAT matrix rows updated:
5 rows move to Implemented (Summary 62/3/5/1/76 = 147).

src/shared/config.c

@@ -1,6 +1,7 @@
 #include "config.h"
 #include "chmod.h"
 #include "delta.h"
+#include "file_list.h"
 #include "log.h"
 #include "protocol.h"
 #include "utils.h"
@@ -92,7 +93,10 @@ static void config_set_defaults(Config* config) {
   config->max_delete = 0;
   config->filters = NULL;
   config->files_from = NULL;
+  config->files_from_set = NULL;
+  config->from0 = false;
   config->cvs_exclude = false;
+  config->per_dir_filter = false;
   config->prune_empty_dirs = false;
   config->one_file_system = false;
   config->relative = false;
@@ -227,6 +231,7 @@ void config_delete(Config* config) {
   free(config->out_format);
   free(config->log_file_format);
   free(config->files_from);
+  file_list_destroy((FileListSet*)config->files_from_set);
   free(config->rsh_command);
   free(config->rsync_path);
   free(config->temp_dir);