feat(p7-output-fs): sparse hole preservation (-S), partial retention (-P), fake-super replay; block-size verified; crtimes/stderr -> Impossible/Divergence (Wave B)

- write_all_sparse: skips all-zero runs >= 4096 bytes via lseek(SEEK_CUR) and
  ftruncates the final size, wired into the atomic temp+rename and --inplace
  paths with no wire change (full image already in memory).
- --partial retention: on a save failure after the temp held data, rename the
  already-written temp to the destination path (best-effort; falls through to
  unlink; never retains when --partial is off) so --append/--append-verify can
  resume; tested by forcing futimens EINVAL with an out-of-range nsec.
- --block-size aliases --delta-block; verified config->delta_block_size is
  honored by the delta engine end-to-end (unit + integration tests).
- fake_super_restore_fd: parses and re-applies user.fastsync.stat fd-relative
  (fchown best-effort/non-root skipped, fchmod, futimens); a save under
  --fake-super now both records and re-applies.
- -N/--crtimes and --stderr=client promoted to a new 'Impossible/Divergence'
  status bucket (Summary: 136/2/4/3/2 = 147).
- cppcheck/clang-format clean; unit 37/37; integration 407 passed.

src/shared/file_receive.c

@@ -87,10 +87,10 @@ static FileSaveResult file_stage_delayed_update(const char* root_directory,
                                   config->preallocate, metadata, preserve_executability,
                                   config->use_fsync, NULL);
   } else {
-    ok =
-        file_to_disk_secure_attrs(staged_path, file->data->data, file->data->size, false, sparse,
-                                  config->preallocate, metadata, preserve_executability, false,
-                                  false, config->use_fsync, file->xattrs, config->fake_super, NULL);
+    ok = file_to_disk_secure_attrs(staged_path, file->data->data, file->data->size, false, sparse,
+                                   config->preallocate, metadata, preserve_executability, false,
+                                   false, config->use_fsync, file->xattrs, config->fake_super,
+                                   false, NULL);
   }
   if (!ok) {
     free(staged_path);
@@ -796,11 +796,11 @@ FileSaveResult file_save_to_disk_full(const char* root_directory, const File* fi
   } else {
     /* The plain no-replace / update / with-fsync engines, plus per-file xattr
        (-X/-A) and --fake-super application on the written fd. */
-    ok = file_to_disk_secure_attrs(disk_path, file->data->data, file->data->size, inplace, sparse,
-                                   config && config->preallocate, metadata, preserve_executability,
-                                   config && config->update, config && config->ignore_existing,
-                                   config && config->use_fsync, file->xattrs,
-                                   config ? config->fake_super : false, confined_temp);
+    ok = file_to_disk_secure_attrs(
+        disk_path, file->data->data, file->data->size, inplace, sparse,
+        config && config->preallocate, metadata, preserve_executability, config && config->update,
+        config && config->ignore_existing, config && config->use_fsync, file->xattrs,
+        config ? config->fake_super : false, config ? config->partial : false, confined_temp);
   }
   free(confined_temp);
   confined_temp = NULL;