fix(cron): respect the platform-conditional decode design in _run_job_script + taskkill kwarg snapshot

cron/scheduler.py deliberately applies utf-8/replace only on Windows via
popen_kwargs (non-Windows keeps locale default per its test contract) —
drop the sweep's unconditional inline kwargs there. Update the gateway
force-kill kwarg snapshot for the new guard.

cron/scheduler.py

@@ -2301,7 +2301,7 @@ def _run_job_script(script_path: str) -> tuple[bool, str]:
         result = subprocess.run(
             argv,
             capture_output=True,
-            text=True, encoding='utf-8', errors='replace',
+            text=True,
             timeout=script_timeout,
             cwd=str(path.parent),
             env=env,

tests/test_windows_subprocess_no_window_flags.py

@@ -508,6 +508,8 @@ def test_gateway_force_kill_hides_taskkill_window(monkeypatch):
             {
                 "capture_output": True,
                 "text": True,
+                "encoding": "utf-8",
+                "errors": "replace",
                 "timeout": 10,
                 "creationflags": _CREATE_NO_WINDOW,
             },