fix: saveSource() liest source_type wieder aus _discoveredData statt Select

Stellt das Original-Verhalten wieder her: Der Typ wird aus den
Auto-Discovery-Daten gelesen, nicht aus dem versteckten Select-Element.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/static/js/app.js

@@ -2851,7 +2851,7 @@ const App = {
         const discovered = this._discoveredData || {};
         const data = {
             name,
-            source_type: document.getElementById('src-type-select') ? document.getElementById('src-type-select').value : (discovered.source_type || 'web_source'),
+            source_type: discovered.source_type || 'web_source',
             category: document.getElementById('src-category').value,
             url: discovered.rss_url || (discovered.source_type === 'telegram_channel' ? (document.getElementById('src-domain').value || null) : null),
             domain: document.getElementById('src-domain').value.trim() || discovered.domain || null,