Fix Twitter/X thread finisher posting with HTML tags

Previously, Twitter/X was posting thread finisher (message ending signature)
with HTML <p> elements hardcoded into the message text. This was because the
thread_finisher content was being used directly without HTML stripping.

This fix wraps the thread_finisher text with stripHtmlValidation() to remove
HTML tags and convert them to plain text, consistent with how other platforms
(Bluesky, Threads, Mastodon) handle this feature.

Changes:
- Added stripHtmlValidation() call for thread_finisher in X provider
- Now matches the implementation pattern used in Bluesky provider
- Ensures thread finisher posts plain text instead of HTML markup

libraries/nestjs-libraries/src/integrations/social/x.provider.ts

@@ -405,7 +405,11 @@ export class XProvider extends SocialAbstract implements SocialProvider {
         await this.runInConcurrent(async () =>
           client.v2.tweet({
             text:
-              postDetails?.[0]?.settings?.thread_finisher! +
+              stripHtmlValidation(
+                'normal',
+                postDetails?.[0]?.settings?.thread_finisher!,
+                true
+              ) +
               '\n' +
               ids[0].releaseURL,
             reply: { in_reply_to_tweet_id: ids[ids.length - 1].postId },