fix: resolve audited dispatch, kernel, and rollout bugs

- re-register the linear family with the operator dispatcher (ASTR_OPS / op_backend / resolve)
- fix bf16 gemv misaligned-address faults and element mispairing for offset weights
- reject misaligned bf16_swiglu inputs with a clear error and fall back in the backend gate
- make the rollout reuse decision, validation, and return atomic under one policy snapshot
- add the documented post-scoring rollout version check
- derive live+1 under the scheduler lock in optimizer_step via apply_weight_update(None, ...)
- reject rollout_max_policy_lag below rollout_interval - 1 at config time
- sync gemv stream-test inputs before switching streams; drop dead loader imports

astrai/extension/loader.py

@@ -20,11 +20,8 @@ import glob
 import importlib
 import logging
 import os
-from functools import cache
 from typing import Dict, List
 
-import torch
-
 logger = logging.getLogger(__name__)
 
 _LIB_DIR = os.path.join(os.path.dirname(__file__), "lib")