feat: 品牌裁剪弹窗/Markdown 行内短代码与详情视频块等

新增：
- BrandCropModal 品牌图裁剪弹窗 + cropImage 工具
- Markdown 行内短代码（inlineShortcodes + remark 插件）
- MdDetails 折叠块、MdVideo 视频块组件
- directiveBlocks/inlineShortcodes 测试

其它：
- 聊天后端（handler/service chat）调整
- Markdown 渲染链路、编辑器、全局样式与品牌相关面板更新

frontend/lib/directiveBlocks.test.ts

@@ -0,0 +1,117 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+import {
+  DETAILS_DEFAULT_TITLE,
+  isDetailsOpen,
+  parseDetailsOpen,
+  parseVideoInput,
+  parseVideoLine,
+  splitContentSegments,
+} from "./directiveBlocks.ts";
+
+describe("parseDetailsOpen / isDetailsOpen", () => {
+  it("开标记整行匹配，标题缺省「点击展开」", () => {
+    assert.equal(isDetailsOpen("[details]"), true);
+    assert.equal(parseDetailsOpen("[details]"), DETAILS_DEFAULT_TITLE);
+    assert.equal(parseDetailsOpen("[details 点击展开看结论]"), "点击展开看结论");
+    assert.equal(isDetailsOpen("[details 标题] 后缀"), false);
+    assert.equal(isDetailsOpen("[details]"), true);
+  });
+});
+
+describe("parseVideoInput", () => {
+  it("BV 号与 B站链接", () => {
+    assert.deepEqual(parseVideoInput("BV1GJ411x7h7"), {
+      provider: "bilibili",
+      id: "BV1GJ411x7h7",
+    });
+    assert.deepEqual(parseVideoInput("https://www.bilibili.com/video/BV1GJ411x7h7/?p=1"), {
+      provider: "bilibili",
+      id: "BV1GJ411x7h7",
+    });
+  });
+  it("YouTube ID 与链接", () => {
+    assert.deepEqual(parseVideoInput("dQw4w9WgXcQ"), {
+      provider: "youtube",
+      id: "dQw4w9WgXcQ",
+    });
+    assert.deepEqual(parseVideoInput("https://youtu.be/dQw4w9WgXcQ"), {
+      provider: "youtube",
+      id: "dQw4w9WgXcQ",
+    });
+    assert.deepEqual(parseVideoInput("https://www.youtube.com/watch?v=dQw4w9WgXcQ"), {
+      provider: "youtube",
+      id: "dQw4w9WgXcQ",
+    });
+  });
+  it("非法输入返回 null", () => {
+    assert.equal(parseVideoInput(""), null);
+    assert.equal(parseVideoInput("hello world"), null);
+    assert.equal(parseVideoInput("https://evil.com/<script>"), null);
+  });
+});
+
+describe("parseVideoLine", () => {
+  it("整行短代码匹配且大小写不敏感", () => {
+    assert.deepEqual(parseVideoLine("[bilibili]BV1GJ411x7h7[/bilibili]"), {
+      provider: "bilibili",
+      id: "BV1GJ411x7h7",
+    });
+    assert.deepEqual(parseVideoLine("[BILIBILI]https://www.bilibili.com/video/BV1GJ411x7h7[/BILIBILI]"), {
+      provider: "bilibili",
+      id: "BV1GJ411x7h7",
+    });
+    assert.deepEqual(parseVideoLine("[youtube]dQw4w9WgXcQ[/youtube]"), {
+      provider: "youtube",
+      id: "dQw4w9WgXcQ",
+    });
+  });
+  it("标签与平台不一致或内容非法时返回 null", () => {
+    assert.equal(parseVideoLine("[bilibili]dQw4w9WgXcQ[/bilibili]"), null);
+    assert.equal(parseVideoLine("[youtube]BV1GJ411x7h7[/youtube]"), null);
+    assert.equal(parseVideoLine("[bilibili]随便[/bilibili]"), null);
+  });
+});
+
+describe("splitContentSegments: details/video", () => {
+  it("[details] 块拆分，正文保留 markdown", () => {
+    const segs = splitContentSegments(
+      "前文\n\n[details 结论]\n**加粗** 内容\n[/details]\n\n后文"
+    );
+    assert.deepEqual(
+      segs.map((s) => s.type),
+      ["md", "details", "md"]
+    );
+    const d = segs[1];
+    assert.equal(d.type === "details" ? d.title : "", "结论");
+    assert.equal(d.type === "details" ? d.body : "", "**加粗** 内容");
+  });
+
+  it("details 嵌套开标签：外层按 md，内层与闭合配对（与 timeline 语义一致）", () => {
+    const segs = splitContentSegments("[details A]\n[details B]\n[/details]");
+    assert.deepEqual(segs.map((s) => s.type), ["md", "details"]);
+  });
+
+  it("未闭合的 details 整段按 md", () => {
+    const segs = splitContentSegments("正文\n\n[details A]\n没有闭合标记");
+    assert.deepEqual(segs.map((s) => s.type), ["md"]);
+  });
+
+  it("代码围栏内伪语法不拆", () => {
+    const segs = splitContentSegments("```\n[details 假的]\n[/details]\n```");
+    assert.deepEqual(segs.map((s) => s.type), ["md"]);
+  });
+
+  it("视频整行拆为 video 段；行内出现不拆", () => {
+    const segs = splitContentSegments(
+      "看这个：\n\n[bilibili]BV1GJ411x7h7[/bilibili]\n\n文中 [youtube]dQw4w9WgXcQ[/youtube] 不拆"
+    );
+    assert.deepEqual(
+      segs.map((s) => s.type),
+      ["md", "video", "md"]
+    );
+    const v = segs[1];
+    assert.equal(v.type === "video" ? v.provider : "", "bilibili");
+    assert.equal(v.type === "video" ? v.id : "", "BV1GJ411x7h7");
+  });
+});