feat: implement icon directive with relative path fallback

Refactor icon rendering to use a custom `marked-directive` instead of
a global icon prefix. This allows icons to use a CSS-based fallback
chain (searching up to 10 directory levels for an `assets/` folder),
making icon paths more robust and removing the need to pass path
prefixes through the component tree.

src/components/Article.tsx

@@ -7,20 +7,17 @@ import {
   onCleanup,
   Show,
   createResource,
-  createMemo,
   createSignal,
 } from "solid-js";
 import { parseMarkdown } from "../markdown";
 import { extractSection } from "../data-loader";
 import mermaid from "mermaid";
 import { getIndexedData } from "../data-loader/file-index";
-import { resolvePath } from "./utils/path";
 import { useNavigateWithParams } from "./useNavigateWithParams";
 
 export interface ArticleProps {
   src: string;
   section?: string; // 指定要显示的标题（不含 #）
-  iconPath?: string; // 图标路径前缀，默认为 "./assets"，空字符串表示禁用
   onLoaded?: () => void;
   onError?: (error: Error) => void;
   class?: string; // 额外的 class 用于样式控制
@@ -83,12 +80,6 @@ export const Article: Component<ArticleProps & ParentProps> = (props) => {
   );
   const [contentDom, setContentDom] = createSignal<HTMLDivElement>();
 
-  // 解析 iconPath，默认为 "./assets"，空字符串表示禁用
-  const iconPrefix = createMemo(() => {
-    if (props.iconPath === "") return undefined; // 空字符串禁用图标前缀
-    return resolvePath(props.src, props.iconPath ?? "./assets");
-  });
-
   createEffect(() => {
     const data = content();
     if (data) {
@@ -144,7 +135,7 @@ export const Article: Component<ArticleProps & ParentProps> = (props) => {
           <div
             class="relative"
             ref={setContentDom}
-            innerHTML={parseMarkdown(content()!, iconPrefix())}
+            innerHTML={parseMarkdown(content()!)}
           />
           {props.children}
         </ArticleDomCtx.Provider>