refactor: 重构 cache 和 inference 参数体系，分离存储与分配

- 合并 GenerationRequest/GenerationParams，统一 max_tokens 参数名
- PagePool/PrefixCache 分离为 Allocator + PrefixCache + PagePool
- 拆分 KV 存储为独立 Storage 类，PagedCache → KVCache，CacheView → KvcacheView
- Allocator.inc_ref 移除 LRU 防止竞争，Storage.write 增加负页防御
- Allocator/PrefixCache/TaskTable 加 threading.Lock 保证线程安全
- server.py uvicorn.run 改为传 app 对象修复导入错误
- benchmark.py 适配 KVCache 新 API

astrai/inference/core/executor.py

@@ -3,7 +3,7 @@ from typing import List, Optional
 
 import torch
 
-from astrai.inference.core.cache import PagedCache
+from astrai.inference.core.cache import KVCache
 from astrai.inference.core.task import Task
 from astrai.inference.sample import sample
 from astrai.model.automodel import AutoModel
@@ -19,7 +19,7 @@ class Executor:
         self,
         model: AutoModel,
         tokenizer: AutoTokenizer,
-        page_cache: PagedCache,
+        page_cache: KVCache,
         device: Optional[str] = None,
         dtype: Optional[torch.dtype] = None,
     ):