chore: import upstream snapshot with attribution

rules/python/patterns.md

@@ -0,0 +1,39 @@
+---
+paths:
+  - "**/*.py"
+  - "**/*.pyi"
+---
+# Python Patterns
+
+> This file extends [common/patterns.md](../common/patterns.md) with Python specific content.
+
+## Protocol (Duck Typing)
+
+```python
+from typing import Protocol
+
+class Repository(Protocol):
+    def find_by_id(self, id: str) -> dict | None: ...
+    def save(self, entity: dict) -> dict: ...
+```
+
+## Dataclasses as DTOs
+
+```python
+from dataclasses import dataclass
+
+@dataclass
+class CreateUserRequest:
+    name: str
+    email: str
+    age: int | None = None
+```
+
+## Context Managers & Generators
+
+- Use context managers (`with` statement) for resource management
+- Use generators for lazy evaluation and memory-efficient iteration
+
+## Reference
+
+See skill: `python-patterns` for comprehensive patterns including decorators, concurrency, and package organization.