fix(plugins): model-provider plugins load under plugins.isolation: host on Windows

The credential-free profile extraction child got HOME but not USERPROFILE.
Windows resolves Path.home() from USERPROFILE only, so the child exited with
"Could not determine home directory" and every user model-provider plugin was
silently dropped under host isolation.

Reported-by: Enough1122

hermes_cli/plugin_host_profiles.py

@@ -82,7 +82,9 @@ def _extract(plugin_dir: Path, module_name: str) -> Dict[str, Any]:
     from hermes_constants import get_hermes_home
     repo_root = str(Path(__file__).resolve().parents[1])
     env = {key: os.environ[key] for key in ("PATH", "LANG", "LC_ALL", "TZ", "SYSTEMROOT") if key in os.environ}
-    env.update(HOME=str(Path.home()), HERMES_HOME=str(get_hermes_home()), PYTHONPATH=repo_root,
+    # Windows resolves Path.home() from USERPROFILE, never HOME: without it the child cannot start.
+    env.update(HOME=str(Path.home()), USERPROFILE=str(Path.home()), HERMES_HOME=str(get_hermes_home()),
+               PYTHONPATH=repo_root,
                **{HOST_PROCESS_ENV: "1"})
     argv = [*host_launcher(), sys.executable, "-m", "hermes_cli.plugin_host_child", "--extract-profiles",
             str(plugin_dir), module_name]