fix: 完善本地与网络图片渲染

packages/renderer/tests/render-markdown.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
 import {
+  extractMarkdownImageSources,
   MarkdownDocumentParseError,
   renderMarkdown
 } from "../src/render-markdown.js";
@@ -210,6 +211,55 @@ option:
     expect(result.bodyHtml).toContain("<script>");
   });
 
+  it("提取图片引用并使用受控资源地址替换", () => {
+    const source =
+      "![本地](./文档.assets/a%20b.png)\n\n![远程](https://example.com/a.png)";
+    expect(extractMarkdownImageSources(source)).toEqual([
+      "./%E6%96%87%E6%A1%A3.assets/a%20b.png",
+      "https://example.com/a.png"
+    ]);
+
+    const result = renderMarkdown(source, {
+      imageSourceMap: new Map([
+        [
+          "./%E6%96%87%E6%A1%A3.assets/a%20b.png",
+          "data:image/png;base64,iVBORw0KGgo="
+        ]
+      ]),
+      warnings: ["远程图片下载失败"]
+    });
+
+    expect(result.bodyHtml).toContain(
+      'class="md-document-image"'
+    );
+    expect(result.bodyHtml).toContain(
+      '<figure class="md-document-image-block">'
+    );
+    expect(result.bodyHtml).toContain(
+      '<figcaption class="md-document-image-caption">本地</figcaption>'
+    );
+    expect(result.bodyHtml).toContain(
+      'src="data:image/png;base64,iVBORw0KGgo="'
+    );
+    expect(result.warnings).toContain("远程图片下载失败");
+  });
+
+  it("只为独立图片块生成可见标题，行内图片保持段落语义", () => {
+    const result = renderMarkdown(
+      "文字 ![行内图](inline.png) 继续\n\n![独立标题](block.png)"
+    );
+
+    expect(result.bodyHtml).toContain(
+      '<p>文字 <img src="inline.png" alt="行内图" class="md-document-image" /> 继续</p>'
+    );
+    expect(result.bodyHtml).not.toContain(
+      "md-document-image-caption\">行内图"
+    );
+    expect(result.bodyHtml).toContain(
+      '<figcaption class="md-document-image-caption">独立标题</figcaption>'
+    );
+  });
+
   it("为重复中文标题生成唯一锚点", () => {
     const result = renderMarkdown(`
 # 章节