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

apps/web/lib/wizard/wizard.ts

@@ -0,0 +1,62 @@
+import type { ProjectCreateRequest } from "@/lib/api/types";
+
+// 立项向导 5 步（UX §6.2）。表单状态用字符串/数组，提交时归一为 ProjectCreateRequest。
+export interface WizardForm {
+  title: string;
+  genre: string;
+  logline: string;
+  sellingPoints: string[];
+  structure: string;
+  premise: string;
+  theme: string;
+}
+
+export const WIZARD_STEPS = 5;
+
+export const emptyWizardForm: WizardForm = {
+  title: "",
+  genre: "",
+  logline: "",
+  sellingPoints: [],
+  structure: "",
+  premise: "",
+  theme: "",
+};
+
+export const GENRES = ["玄幻", "仙侠", "都市", "科幻", "历史", "悬疑"];
+export const STRUCTURES = ["三幕", "故事圈", "雪花"];
+export const SELLING_POINT_PRESETS = ["逆袭", "打脸", "系统流", "双男主", "群像"];
+
+// 每一步可否前进：仅第 1 步（书名）必填，其余可空着继续（草稿式立项）。
+export function canAdvance(step: number, form: WizardForm): boolean {
+  if (step === 1) return form.title.trim().length > 0;
+  return true;
+}
+
+// 整个向导可否提交：书名必填。
+export function canSubmit(form: WizardForm): boolean {
+  return form.title.trim().length > 0;
+}
+
+export function clampStep(step: number): number {
+  if (step < 1) return 1;
+  if (step > WIZARD_STEPS) return WIZARD_STEPS;
+  return step;
+}
+
+// 归一为后端请求体（snake_case，空值落 null/省略）。
+export function toCreateRequest(form: WizardForm): ProjectCreateRequest {
+  const trim = (s: string): string | null => {
+    const v = s.trim();
+    return v.length > 0 ? v : null;
+  };
+  return {
+    title: form.title.trim(),
+    genre: trim(form.genre),
+    logline: trim(form.logline),
+    premise: trim(form.premise),
+    theme: trim(form.theme),
+    selling_points: form.sellingPoints,
+    structure: trim(form.structure),
+  };
+}