refactor(persistence): 24 hand-rolled atomic JSON/text writers go through utils.atomic_json_write / atomic_write_text

Each copy re-implemented temp+replace by hand and lacked one or more of
fsync, symlink preservation, atomic_replace's Windows-contention retry and
EXDEV/bind-mount fallback, mode preservation, or interrupt-safe temp
cleanup. Three (gateway/session_persistence, cron/suggestions,
agent/shell_hooks) were verbatim inlines of utils._atomic_write; two
modules defined their own directory-fsync helper, now utils.fsync_directory.
plugins/google_meet/_jsonfile.write_json_atomic is deleted (callers use the
canonical helper directly).

Behavior change: every one of these writers now fsyncs the payload, keeps a
pre-existing target's mode, cleans its temp file on BaseException, and
survives Windows AV/indexer contention and cross-device renames the way
config writes already did. cron/suggestions.json is 0600 from creation
(previously chmod'ed after the replace). Skipped on purpose: cron/jobs.py
two-phase staging, gateway/status._write_json_excl (create-only lock),
kanban_transfer staging (not atomic writers); tools/skill_usage.
_write_suppressed_names lives inside a PLUGIN-COMPAT block.

hermes_cli/profiles.py

@@ -1591,15 +1591,12 @@ def import_profile(archive_path: str, name: Optional[str] = None) -> Path:
 # Rename
 
 def _atomic_write_json(path: Path, data: dict) -> bool:
-    """Write *data* to *path* via a sibling ``.tmp`` + rename. Returns False (tmp cleaned) on OSError."""
-    tmp = path.with_suffix(path.suffix + ".tmp")
+    """Atomic rewrite of a third-party JSON config; False on OSError (nothing partially written)."""
+    from utils import atomic_json_write
     try:
-        tmp.write_text(json.dumps(data, indent=2, ensure_ascii=False) + "\n", encoding="utf-8")
-        tmp.replace(path)
+        atomic_json_write(path, data)
         return True
     except OSError:
-        with contextlib.suppress(OSError):
-            tmp.unlink(missing_ok=True)
         return False