feat(web): Scope B B2 — 工具箱原文输入 + 4 新生成器预览渲染

buildGenerateRequest 转发 text（扩写/降AI/拆书原文，text_input 策略；空白省略）。
mapPreview 处理单对象产物：续写/扩写/降AI（{text}→单 body 卡）、拆书
BookTeardownResult（structure 作标题 + themes/archetypes/hooks 列表字段）——
绕过 firstArrayEntry 的「记录列表」假设，使 4 新生成器声明驱动表单/预览自动可渲染。
原文 textarea 字段（name=text）由既有 FormField 渲染，无需改组件。

apps/web/lib/toolbox/toolbox.test.ts

@@ -74,6 +74,18 @@ describe("buildGenerateRequest", () => {
   it("defaults brief to empty string", () => {
     expect(buildGenerateRequest({})).toEqual({ brief: "" });
   });
+
+  it("forwards trimmed text (扩写/降AI/拆书 原文输入)", () => {
+    expect(
+      buildGenerateRequest({ brief: "扩写", text: "  原始正文片段  " }),
+    ).toEqual({ brief: "扩写", text: "原始正文片段" });
+  });
+
+  it("omits blank/whitespace-only text", () => {
+    expect(buildGenerateRequest({ brief: "x", text: "   " })).toEqual({
+      brief: "x",
+    });
+  });
 });
 
 describe("previewRows", () => {
@@ -137,6 +149,37 @@ describe("mapPreview", () => {
   it("yields no items for empty preview", () => {
     expect(mapPreview("IdeaListResult", undefined).items).toEqual([]);
   });
+
+  it("maps a text-only result (续写/扩写/降AI) into a single body item", () => {
+    for (const kind of ["ContinuationResult", "PolishResult", "DeAiResult"]) {
+      const model = mapPreview(kind, { text: "一段续写/改写后的正文" });
+      expect(model.items).toHaveLength(1);
+      expect(model.items[0]?.heading).toBeNull();
+      expect(model.items[0]?.body).toBe("一段续写/改写后的正文");
+    }
+  });
+
+  it("maps BookTeardownResult structured fields into one card", () => {
+    const model = mapPreview("BookTeardownResult", {
+      themes: ["逆袭", "复仇"],
+      archetypes: ["废柴主角"],
+      structure: "三幕递进",
+      hooks: ["开局打脸", "扮猪吃虎"],
+    });
+    expect(model.items).toHaveLength(1);
+    const item = model.items[0];
+    expect(item?.heading).toBe("三幕递进");
+    const byLabel = (label: string) =>
+      item?.fields.find((f) => f.label === label)?.value;
+    expect(byLabel("主题")).toBe("逆袭；复仇");
+    expect(byLabel("人物原型")).toBe("废柴主角");
+    expect(byLabel("钩子套路")).toBe("开局打脸；扮猪吃虎");
+  });
+
+  it("yields no items for an empty text result", () => {
+    expect(mapPreview("ContinuationResult", { text: "" }).items).toEqual([]);
+    expect(mapPreview("ContinuationResult", undefined).items).toEqual([]);
+  });
 });
 
 describe("resolveLegacyRoute", () => {