add: chongming-cache 统一缓存工具（diskcache / redis 双后端，dict-like 接口）

src/chongming_cache/backends/disk.py

@@ -0,0 +1,60 @@
+"""diskcache 后端：基于 SQLite 的本地持久化缓存，多进程安全。"""
+
+from pathlib import Path
+from typing import Any, Iterator
+
+from diskcache import Cache as DiskCache
+
+from chongming_cache.backends.base import CacheBackend
+
+
+class DiskBackend(CacheBackend):
+    """包装 diskcache.Cache，提供统一接口。
+
+    Args:
+        path: 缓存目录（SQLite 数据文件所在目录），父目录不存在时自动创建。
+    """
+
+    def __init__(self, path: str | Path):
+        self._cache = DiskCache(path)
+
+    @property
+    def client(self) -> DiskCache:
+        """底层 diskcache.Cache 实例（逃生口）。"""
+        return self._cache
+
+    def __contains__(self, key) -> bool:
+        return key in self._cache
+
+    def __getitem__(self, key) -> Any:
+        return self._cache[key]
+
+    def __setitem__(self, key, value) -> None:
+        self._cache[key] = value
+
+    def __delitem__(self, key) -> None:
+        del self._cache[key]
+
+    def __len__(self) -> int:
+        return len(self._cache)
+
+    def __iter__(self) -> Iterator:
+        return iter(self._cache)
+
+    def get(self, key, default=None) -> Any:
+        return self._cache.get(key, default)
+
+    def set(self, key, value, expire: float | None = None) -> None:
+        self._cache.set(key, value, expire=expire)
+
+    def touch(self, key, expire: float | None = None) -> bool:
+        return self._cache.touch(key, expire=expire)
+
+    def delete(self, key) -> bool:
+        return self._cache.delete(key)
+
+    def clear(self) -> None:
+        self._cache.clear()
+
+    def close(self) -> None:
+        self._cache.close()