feat: convert strikethrough and inline-style emphasis when extracting

Three additions to ContentExtractor's turndown setup so semantic
formatting reaches the RAG corpus:

- GFM strikethrough plugin: handles <s>, <del>, <strike> tags. Before,
  those tags were dropped silently, leaving struck-through text mixed
  with the new text undistinguishable.

- Custom rule for <span style="..."> emphasis. WordPress WYSIWYG and
  Divi/Elementor emit bold/italic/strikethrough as inline-style spans
  instead of semantic tags; the rule matches font-weight (bold or
  numeric 600+), font-style: italic, and text-decoration: line-through
  and wraps the content with the corresponding markdown syntax. Important
  for artdent's price tables, where the old discounted price was rendered
  as `<span style="text-decoration: line-through;">10.000 Ft</span>` —
  the previous extractor lost that distinction.

- Keep <u>, <mark>, <sup>, <sub>, <kbd> as inline HTML in the markdown
  output. Markdown has no native syntax for these so they'd otherwise be
  dropped to plain text; keeping the tags preserves the semantic
  information for downstream RAG/embedding.

src/scraper/ContentExtractor.ts

@@ -21,6 +21,38 @@ export class ContentExtractor {
     // /araink/ price table on artdent was being saved as a flat list of
     // numbers, which makes it useless for RAG.
     this.turndownService.use(turndownGfm.tables);
+    // GFM strikethrough handles <s>, <del>, <strike>. Without it the slash
+    // information is silently dropped, which on artdent's discounted prices
+    // (`<s>10.000 Ft</s> 7.000 Ft`) leaves both prices side by side with
+    // no indication which is the old one.
+    this.turndownService.use(turndownGfm.strikethrough);
+
+    // WordPress WYSIWYG editors and Divi/Elementor often emit emphasis as
+    // <span style="..."> rather than semantic tags. Map the common ones to
+    // markdown so the formatting reaches the RAG corpus.
+    this.turndownService.addRule('inlineStyleSpan', {
+      filter: (node: any) => {
+        if (node.nodeName !== 'SPAN') return false;
+        const style = (node.getAttribute('style') || '').toLowerCase();
+        return /text-decoration\s*:\s*[^;]*line-through/.test(style)
+            || /font-weight\s*:\s*(bold|[6-9]00)/.test(style)
+            || /font-style\s*:\s*italic/.test(style);
+      },
+      replacement: (content: string, node: any) => {
+        const style = (node.getAttribute('style') || '').toLowerCase();
+        let out = content;
+        // Apply in inside-out order so the final string looks like ~~**X**~~.
+        if (/font-style\s*:\s*italic/.test(style)) out = `_${out}_`;
+        if (/font-weight\s*:\s*(bold|[6-9]00)/.test(style)) out = `**${out}**`;
+        if (/text-decoration\s*:\s*[^;]*line-through/.test(style)) out = `~~${out}~~`;
+        return out;
+      }
+    });
+
+    // Markdown has no native syntax for these inline elements. Keep them as
+    // raw HTML so the semantic info isn't lost (most markdown renderers and
+    // embedding tokenizers handle inline HTML fine).
+    this.turndownService.keep(['u', 'mark', 'sup', 'sub', 'kbd']);
   }
 
   /**