Security: stored XSS via social group discussion thread title

Render the discussion thread title as auto-escaped text instead of raw
v-html in usergroup/GroupDiscussions.vue. A thread title is plain text and
needs no markup, so escaping it closes the stored-XSS sink where an
attacker-supplied title executed in every group member's browser on page
load.

Refs GHSA-9mpp-78g5-c22m

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: AngelFQC

assets/vue/components/usergroup/GroupDiscussions.vue

@@ -18,10 +18,7 @@
         @click="selectDiscussion(discussion)"
       >
         <div class="discussion-content">
-          <div
-            class="discussion-title"
-            v-html="discussion.title"
-          ></div>
+          <div class="discussion-title">{{ discussion.title }}</div>
           <div class="discussion-details">
             <i class="mdi mdi-message-reply-text icon"></i>
             <span>{{ discussion.repliesCount }} {{ t("Replies") }}</span>