fix(profiling): sort import + move expressions to env vars for zizmor

Pre-commit Quality gate flagged two issues:

1. ruff/isort: `from numbers import Real` must sort after
   `from collections.abc import Callable` (stdlib alphabetical order).

2. zizmor (high): `github.head_ref`, `github.ref_name`,
   `github.event.inputs.git_ref`, and `github.event.pull_request.head.sha`
   were expanded directly in `run:` shell blocks, which zizmor flags as
   attacker-controllable. Move all four into job-level `env:` vars
   (GIT_REF, PR_NUMBER, HOST_GIT_COMMIT) so the shell only sees env-var
   references — the same pattern the workflow already uses for
   PROFILE_MODE, POLICY_FILTER, etc.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lerobot/utils/profiling_utils.py

@@ -22,15 +22,16 @@ import io
 import json
 import pstats
 import statistics
-from numbers import Real
 from collections.abc import Callable
 from dataclasses import dataclass, field
+from numbers import Real
 from pathlib import Path
 from typing import Any
 
 import torch
 from torch.utils.data._utils.collate import default_collate
 
+
 def ensure_dir(path: Path) -> Path:
     path.mkdir(parents=True, exist_ok=True)
     return path