feat: add RRULE parsing to shared package and improve ProposedEventCard UI

- Add rrule library to shared package for RRULE string parsing
- Add rruleHelpers.ts with parseRRule() returning freq, until, count, interval, byDay
- Add formatters.ts with German date/time formatters for client and server
- Extend CreateEventDTO with exceptionDates field for proposals
- Extend ChatModel schema with exceptionDates, deleteMode, occurrenceDate
- Update proposeUpdateEvent tool to support isRecurring and recurrenceRule params
- ProposedEventCard now shows green "Neue Ausnahme" and "Neues Ende" text
- Add Sport test scenario with dynamic exception and UNTIL responses
- Update CLAUDE.md documentation

apps/server/src/controllers/ChatController.ts

@@ -35,6 +35,10 @@ export class ChatController {
     try {
       const userId = req.user!.userId;
       const { conversationId, messageId } = req.params;
+
+      // DEBUG: Log incoming request body to trace deleteMode issue
+      log.debug({ body: req.body }, "confirmEvent request body");
+
       const {
         proposalId,
         action,