feat: 初始化PyFlowX轻量级DAG任务调度库

实现完整的DAG任务调度核心功能，包括：
1.  支持同步/异步/线程三种执行策略
2.  自动上下文注入，无需手动绑定任务依赖
3.  内置状态后端，支持断点续跑
4.  提供完整的测试用例与示例代码
5.  添加CI/CD配置与发布流程

tests/test_context.py

@@ -0,0 +1,89 @@
+"""Tests for context injection rules."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+import pyflowx as px
+from pyflowx.context import build_call_args, describe_injection
+from pyflowx.errors import InjectionError
+
+
+def test_inject_by_parameter_name() -> None:
+    def fn(a: int, b: str) -> str:
+        return f"{a}{b}"
+
+    spec = px.TaskSpec("c", fn, ("a", "b"))
+    args, kwargs = build_call_args(spec, {"a": 1, "b": "x"})
+    assert args == ()
+    assert kwargs == {"a": 1, "b": "x"}
+
+
+def test_inject_context_annotation() -> None:
+    def fn(ctx: px.Context) -> int:
+        return len(ctx)
+
+    spec = px.TaskSpec("agg", fn, ("a", "b"))
+    args, kwargs = build_call_args(spec, {"a": 1, "b": 2, "c": 99})
+    # Only the task's own deps are passed.
+    assert kwargs == {"ctx": {"a": 1, "b": 2}}
+
+
+def test_inject_var_keyword() -> None:
+    def fn(**kwargs: Any) -> int:
+        return sum(kwargs.values())
+
+    spec = px.TaskSpec("agg", fn, ("a", "b"))
+    args, kwargs = build_call_args(spec, {"a": 1, "b": 2})
+    assert kwargs == {"a": 1, "b": 2}
+
+
+def test_static_args_and_kwargs() -> None:
+    def fn(uid: int, source: str) -> str:
+        return f"{source}:{uid}"
+
+    spec = px.TaskSpec("fetch", fn, args=(42,), kwargs={"source": "api"})
+    args, kwargs = build_call_args(spec, {})
+    assert args == (42,)
+    assert kwargs == {"source": "api"}
+
+
+def test_default_param_not_required() -> None:
+    def fn(a: int, flag: bool = True) -> int:
+        return a if flag else 0
+
+    spec = px.TaskSpec("t", fn, ("a",))
+    args, kwargs = build_call_args(spec, {"a": 5})
+    assert kwargs == {"a": 5}
+
+
+def test_unresolved_required_param_raises() -> None:
+    def fn(a: int, missing: str) -> None:
+        return None
+
+    spec = px.TaskSpec("t", fn, ("a",))
+    with pytest.raises(InjectionError) as exc_info:
+        build_call_args(spec, {"a": 1})
+    assert "missing" in str(exc_info.value)
+
+
+def test_static_kwargs_collide_with_dependency() -> None:
+    def fn(a: int) -> int:
+        return a
+
+    spec = px.TaskSpec("t", fn, ("a",), kwargs={"a": 99})
+    with pytest.raises(InjectionError):
+        build_call_args(spec, {"a": 1})
+
+
+def test_describe_injection() -> None:
+    def fn(a: int, ctx: px.Context, flag: bool = False) -> None:
+        return None
+
+    spec = px.TaskSpec("t", fn, ("a",))
+    desc = describe_injection(spec)
+    assert "a=<result:a>" in desc
+    assert "ctx=<Context>" in desc
+    assert "flag=<default>" in desc