feat: M1 — 立项→写章草稿(SSE)→自动保存；连一家 provider

- 薄自建 LLM 网关：OpenAI 兼容适配器(DeepSeek) + instructor 结构化输出 + usage_ledger 记账 + 档位路由
- 记忆服务 assemble：确定性选择(显式+主角+近况) + 渲染卡 + 缓存断点(中性文本)
- LangGraph 写章节点 + Postgres checkpointer + SSE 归一(token/done/error)
- API：立项 + 写章 draft(SSE) + PUT 自动保存 + 提供商凭据(Fernet 加密/测试连接)
- 前端：AppShell + 作品库 + 5 步立项向导 + 写作工作台(流式打字机+自动保存) + 设置页
- M1 E2E：真实 DB + mock 网关零 token 走通闭环

packages/core/pyproject.toml

@@ -0,0 +1,26 @@
+[project]
+name = "ww-core"
+version = "0.0.0"
+requires-python = ">=3.12"
+dependencies = [
+  "langgraph>=0.2.40",
+  "langgraph-checkpoint-postgres>=2.0",
+  "pydantic>=2.7",
+  "ww-shared",
+  "ww-config",
+  "ww-db",
+  "ww-llm-gateway",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["ww_core"]
+
+[tool.uv.sources]
+ww-shared = { workspace = true }
+ww-config = { workspace = true }
+ww-db = { workspace = true }
+ww-llm-gateway = { workspace = true }