refactor(js): 4. Iteration – Card-Preview-Helper, Button-Loading, Stream-Events vereinfacht

Neue Helper:
- _renderCardPreview(): Gemeinsamer Helper für Agent/Session-Card-Vorschau
  (ersetzt renderAgentInCard + renderSessionSelectCard Duplikate)
- withButtonLoading(btn, text, fn): Eliminiert ~15x identisches
  disable/text/try/finally/reset Pattern in allen Pages
- formatDate(): Nach ui-helpers.js verschoben (war in dashboard.js)
- createMDE(): maxHeight-Option hinzugefügt

Dedupliziert:
- handleStreamEvent: 12 Preparer/Review/Finalizer cases → 7 durch
  case-Grouping (start/text/tool_use shared)
- _escCmdAttr() entfernt → nutzt jetzt esc() aus ui-helpers.js
- feInitEasyMDE() nutzt jetzt createMDE() statt eigener EasyMDE-Init

Betroffene Dateien: ui-helpers.js, chat.js, commands-ui.js,
file-explorer.js, dashboard.js, session-page.js, cronjob-page.js,
profile-page.js, admin-page.js, server-settings-page.js, settings-page.js

wwwroot/js/chat.js

@@ -73,16 +73,17 @@ function handleStreamEvent(eventType, data) {
       addChoiceBubble(data.toolCallId, data.question, data.choices);
       break;
 
-    case 'preparer_start':
+    // Preparer / Review / Finalizer events (shared pattern)
+    case 'preparer_start': case 'review_start': case 'finalizer_start':
       endStreamBubble();
-      addReviewBubble('start', data, 'preparer');
+      addReviewBubble('start', data, eventType.split('_')[0] === 'review' ? undefined : eventType.split('_')[0]);
       break;
 
-    case 'preparer_text':
+    case 'preparer_text': case 'review_text': case 'finalizer_text':
       appendToReviewText(data.text);
       break;
 
-    case 'preparer_tool_use':
+    case 'preparer_tool_use': case 'review_tool_use': case 'finalizer_tool_use':
       addReviewToolUse(data);
       break;
 
@@ -90,19 +91,6 @@ function handleStreamEvent(eventType, data) {
       finalizeReviewBubble(data.forwarded ? 'forwarded' : 'query', data, 'preparer');
       break;
 
-    case 'review_start':
-      endStreamBubble();
-      addReviewBubble('start', data);
-      break;
-
-    case 'review_text':
-      appendToReviewText(data.text);
-      break;
-
-    case 'review_tool_use':
-      addReviewToolUse(data);
-      break;
-
     case 'review_feedback':
       finalizeReviewBubble('feedback', data);
       break;
@@ -111,19 +99,6 @@ function handleStreamEvent(eventType, data) {
       finalizeReviewBubble('approved', data);
       break;
 
-    case 'finalizer_start':
-      endStreamBubble();
-      addReviewBubble('start', data, 'finalizer');
-      break;
-
-    case 'finalizer_text':
-      appendToReviewText(data.text);
-      break;
-
-    case 'finalizer_tool_use':
-      addReviewToolUse(data);
-      break;
-
     case 'finalizer_done':
       finalizeReviewBubble('done', data, 'finalizer');
       break;