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.

tools/bot_live_delivery.py

@@ -10,10 +10,11 @@ from __future__ import annotations
 import json
 import os
 import re
-import tempfile
 import time
 import uuid
 from contextlib import contextmanager
+
+from utils import atomic_json_write, fsync_directory
 from pathlib import Path
 from typing import Any
 
@@ -73,25 +74,14 @@ def _root(home: Path | str) -> Path:
     return Path(home).resolve() / "runtime" / DELIVERY_DIR_NAME
 
 
-def _fsync_dir(path: Path) -> None:
-    # Windows cannot open directories with os.open; file fsync still applies.
-    if os.name == "nt":
-        return
-    fd = os.open(path, os.O_RDONLY)
-    try:
-        os.fsync(fd)
-    finally:
-        os.close(fd)
-
-
 @contextmanager
 def _locked(home: Path | str):
     root = _root(home)
     root.parent.mkdir(parents=True, exist_ok=True)
     root.mkdir(mode=0o700, exist_ok=True)
     root.chmod(0o700)
-    _fsync_dir(root.parent)
-    _fsync_dir(root.parent.parent)
+    fsync_directory(root.parent)
+    fsync_directory(root.parent.parent)
     lock = root / ".lock"
     fd = os.open(lock, os.O_CREAT | os.O_WRONLY, 0o600)
     os.close(fd)
@@ -107,16 +97,7 @@ def _read(path: Path) -> dict[str, Any] | None:
 
 
 def _write(path: Path, record: dict[str, Any]) -> None:
-    fd, temporary = tempfile.mkstemp(dir=path.parent, prefix=".delivery-")
-    try:
-        with os.fdopen(fd, "w", encoding="utf-8") as stream:
-            json.dump(record, stream, ensure_ascii=False, sort_keys=True)
-            stream.flush()
-            os.fsync(stream.fileno())
-        os.replace(temporary, path)
-        _fsync_dir(path.parent)
-    finally:
-        Path(temporary).unlink(missing_ok=True)
+    atomic_json_write(path, record, indent=None, sort_keys=True, fsync_dir=True)
 
 
 def deliver_to_live_owner(