feat(system):优化后端

1.新增后端测试
2.增加了后端的加密
3.增加了i18n（国际化）

tests/unit/test_utils_retry.py

@@ -0,0 +1,87 @@
+"""``retry_on_retryable_error`` 装饰器：覆盖同步/异步、重试次数、退避语义。"""
+
+import asyncio
+
+import pytest
+
+from kilostar.utils.error import NonRetryableError, RetryableError
+from kilostar.utils.retry import retry_on_retryable_error
+
+
+def test_sync_retries_until_success(monkeypatch):
+    sleep_calls: list[float] = []
+    monkeypatch.setattr("time.sleep", lambda s: sleep_calls.append(s))
+
+    counter = {"n": 0}
+
+    @retry_on_retryable_error(max_retries=3, base_delay=1)
+    def flaky() -> str:
+        counter["n"] += 1
+        if counter["n"] < 3:
+            raise RetryableError("temp")
+        return "ok"
+
+    assert flaky() == "ok"
+    assert counter["n"] == 3
+    # 第 1、2 次失败前各 sleep 一次：base * 2**0 = 1, base * 2**1 = 2
+    assert sleep_calls == [1, 2]
+
+
+def test_sync_reraises_after_exhaustion(monkeypatch):
+    monkeypatch.setattr("time.sleep", lambda _s: None)
+
+    @retry_on_retryable_error(max_retries=2, base_delay=1)
+    def always_fail() -> None:
+        raise RetryableError("nope")
+
+    with pytest.raises(RetryableError):
+        always_fail()
+
+
+def test_sync_does_not_retry_on_non_retryable(monkeypatch):
+    sleep_calls: list[float] = []
+    monkeypatch.setattr("time.sleep", lambda s: sleep_calls.append(s))
+
+    @retry_on_retryable_error(max_retries=5, base_delay=1)
+    def boom() -> None:
+        raise NonRetryableError("hard")
+
+    with pytest.raises(NonRetryableError):
+        boom()
+    assert sleep_calls == []
+
+
+async def test_async_retries_until_success(monkeypatch):
+    sleep_calls: list[float] = []
+
+    async def fake_sleep(s: float) -> None:
+        sleep_calls.append(s)
+
+    monkeypatch.setattr(asyncio, "sleep", fake_sleep)
+
+    counter = {"n": 0}
+
+    @retry_on_retryable_error(max_retries=4, base_delay=2)
+    async def flaky() -> int:
+        counter["n"] += 1
+        if counter["n"] < 2:
+            raise RetryableError("temp")
+        return 42
+
+    assert await flaky() == 42
+    assert counter["n"] == 2
+    assert sleep_calls == [2]  # base * 2**0
+
+
+async def test_async_reraises_after_exhaustion(monkeypatch):
+    async def fake_sleep(_s: float) -> None:
+        return None
+
+    monkeypatch.setattr(asyncio, "sleep", fake_sleep)
+
+    @retry_on_retryable_error(max_retries=2, base_delay=1)
+    async def boom() -> None:
+        raise RetryableError("nope")
+
+    with pytest.raises(RetryableError):
+        await boom()