chore: bootstrap project scaffolding

Add architecture doc (research-wiki/ARCHITECTURE.md), CLAUDE.md with
tiered SOP for Fable 5, adapted .claude skills/hooks/settings, package
skeleton (src/polygateway), pyproject with import-linter contracts,
Makefile, .env.example and smoke test.

tests/unit/test_package.py

@@ -0,0 +1,7 @@
+"""包基线冒烟测试：可导入、版本号存在。"""
+
+import polygateway
+
+
+def test_package_importable_with_version() -> None:
+    assert polygateway.__version__ == "0.1.0"