feat: add embed snippet to profile settings

crates/adapters/template-askama/templates/profile_settings.html

@@ -56,4 +56,10 @@
 
   <button type="submit">Save</button>
 </form>
+
+<section style="margin-top:2rem;padding-top:1rem;border-top:1px solid rgba(255,255,255,0.1)">
+  <h3>Embed widget</h3>
+  <p style="font-size:.85em;opacity:.7;margin-bottom:.5rem">Add your diary to your blog or website:</p>
+  <pre style="background:rgba(255,255,255,0.06);padding:12px;border-radius:8px;font-size:.8em;overflow-x:auto;white-space:pre-wrap;word-break:break-all"><code>&lt;iframe src="{{ embed_url }}" width="100%" height="600" style="border:none;border-radius:8px" loading="lazy"&gt;&lt;/iframe&gt;</code></pre>
+</section>
 {% endblock %}