Add support for headings inside wrap blocks (#133)

Modified processPostContent to find headings in two locations:
1. Direct descendants of body (existing behavior)
2. Inside .wrap blocks (new - for email filtering via [wrap=no-email])

This allows table of contents to include headings that are wrapped for
email filtering purposes, which is a common use case in Discourse.

The headings are combined and sorted by document order to maintain proper
structure in the TOC.

javascripts/discourse/services/toc-processor.js

@@ -77,10 +77,21 @@ export default class TocProcessor extends Service {
     if (this.containsHeadings(content)) {
       const parsedPost = new DOMParser().parseFromString(content, "text/html");
 
-      // direct descendants to avoid picking up headings in quotes
-      const headings = parsedPost.querySelectorAll(
-        "body > h1,body > h2,body > h3,body > h4,body > h5"
-      );
+      // Find headings that are either:
+      // 1. Direct descendants of body (to avoid picking up headings in quotes)
+      // 2. Inside wrap blocks (which are used for email filtering with [wrap=no-email])
+      const selector =
+        "body > :is(h1, h2, h3, h4, h5), body > :is(.wrap, .d-wrap) :is(h1, h2, h3, h4, h5)";
+
+      const allHeadings = parsedPost.querySelectorAll(selector);
+
+      // Convert NodeList to Array and sort by document order
+      const headings = Array.from(allHeadings).sort((a, b) => {
+        // eslint-disable-next-line no-bitwise
+        return a.compareDocumentPosition(b) & Node.DOCUMENT_POSITION_FOLLOWING
+          ? -1
+          : 1;
+      });
 
       if (headings.length < settings.TOC_min_heading) {
         this.setOverlayVisible(false);