fix: register marked extensions once via module script

Move marked.use() calls from instance script to <script context="module">
so extensions are registered once when the module is first imported,
rather than re-stacking on every Markdown component mount.

Author: Algorithm5838

src/lib/components/chat/Messages/Markdown.svelte

@@ -1,16 +1,37 @@
-<script>
+<script context="module">
 	import { marked } from 'marked';
-	import { replaceTokens, processResponseContent } from '$lib/utils';
-	import { user } from '$lib/stores';
 
-	import markedExtension from '$lib/utils/marked/extension';
 	import markedKatexExtension from '$lib/utils/marked/katex-extension';
+	import markedExtension from '$lib/utils/marked/extension';
+	import citationExtension from '$lib/utils/marked/citation-extension';
+	import footnoteExtension from '$lib/utils/marked/footnote-extension';
 	import { disableSingleTilde } from '$lib/utils/marked/strikethrough-extension';
 	import { mentionExtension } from '$lib/utils/marked/mention-extension';
 
+	const options = {
+		throwOnError: false,
+		breaks: true
+	};
+
+	marked.use(markedKatexExtension(options));
+	marked.use(markedExtension(options));
+	marked.use(citationExtension(options));
+	marked.use(footnoteExtension(options));
+	marked.use(disableSingleTilde);
+	marked.use({
+		extensions: [
+			mentionExtension({ triggerChar: '@' }),
+			mentionExtension({ triggerChar: '#' }),
+			mentionExtension({ triggerChar: '$' })
+		]
+	});
+</script>
+
+<script>
+	import { replaceTokens, processResponseContent } from '$lib/utils';
+	import { user } from '$lib/stores';
+
 	import MarkdownTokens from './Markdown/MarkdownTokens.svelte';
-	import footnoteExtension from '$lib/utils/marked/footnote-extension';
-	import citationExtension from '$lib/utils/marked/citation-extension';
 
 	export let id = '';
 	export let content;
@@ -35,24 +56,6 @@
 
 	let tokens = [];
 
-	const options = {
-		throwOnError: false,
-		breaks: true
-	};
-
-	marked.use(markedKatexExtension(options));
-	marked.use(markedExtension(options));
-	marked.use(citationExtension(options));
-	marked.use(footnoteExtension(options));
-	marked.use(disableSingleTilde);
-	marked.use({
-		extensions: [
-			mentionExtension({ triggerChar: '@' }),
-			mentionExtension({ triggerChar: '#' }),
-			mentionExtension({ triggerChar: '$' })
-		]
-	});
-
 	$: (async () => {
 		if (content) {
 			tokens = marked.lexer(