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.

.gitignore

@@ -0,0 +1,32 @@
+# 参考项目：只读且不入库（CLAUDE.md 硬性规则）
+reference/
+
+# 密钥与工程配置（模板 .env.example 入库）
+.env
+.env.*
+!.env.example
+
+# 运行产物（不提交）
+data/
+logs/
+tests/outputs/
+results/
+*.db
+*.sqlite3
+
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+build/
+dist/
+.pytest_cache/
+.ruff_cache/
+.coverage
+htmlcov/
+
+# Claude Code 本地配置（项目级 settings.json 入库）
+.claude/settings.local.json
+
+# 系统
+.DS_Store