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/client/src/components/ProposedEventCard.tsx

@@ -1,34 +1,15 @@
 import { View, Text, Pressable } from "react-native";
-import { ProposedEventChange, RecurringDeleteMode } from "@calchat/shared";
+import { Feather } from "@expo/vector-icons";
+import { ProposedEventChange, parseRRule, formatDate } from "@calchat/shared";
 import { useThemeStore } from "../stores/ThemeStore";
 import { EventCardBase } from "./EventCardBase";
 
-const DELETE_MODE_LABELS: Record<RecurringDeleteMode, string> = {
-  single: "Nur dieses Vorkommen",
-  future: "Dieses & zukuenftige",
-  all: "Alle Vorkommen",
-};
-
 type ProposedEventCardProps = {
   proposedChange: ProposedEventChange;
   onConfirm: () => void;
   onReject: () => void;
 };
 
-const DeleteModeBadge = ({ mode }: { mode: RecurringDeleteMode }) => {
-  const { theme } = useThemeStore();
-  return (
-    <View
-      className="self-start px-2 py-1 rounded-md mb-2"
-      style={{ backgroundColor: theme.rejectButton }}
-    >
-      <Text style={{ color: theme.buttonText }} className="text-xs font-medium">
-        {DELETE_MODE_LABELS[mode]}
-      </Text>
-    </View>
-  );
-};
-
 const ConfirmRejectButtons = ({
   isDisabled,
   respondedAction,
@@ -84,15 +65,21 @@ export const ProposedEventCard = ({
   onConfirm,
   onReject,
 }: ProposedEventCardProps) => {
+  const { theme } = useThemeStore();
   const event = proposedChange.event;
-  // respondedAction is now part of the proposedChange
   const isDisabled = !!proposedChange.respondedAction;
 
-  // Show delete mode badge for delete actions on recurring events
-  const showDeleteModeBadge =
+  // For delete/single action, the occurrenceDate becomes a new exception
+  const newExceptionDate =
     proposedChange.action === "delete" &&
-    event?.isRecurring &&
-    proposedChange.deleteMode;
+    proposedChange.deleteMode === "single" &&
+    proposedChange.occurrenceDate;
+
+  // For update actions, check if a new UNTIL date is being set
+  const newUntilDate =
+    proposedChange.action === "update" &&
+    event?.recurrenceRule &&
+    parseRRule(event.recurrenceRule)?.until;
 
   if (!event) {
     return null;
@@ -108,8 +95,33 @@ export const ProposedEventCard = ({
         description={event.description}
         isRecurring={event.isRecurring}
       >
-        {showDeleteModeBadge && (
-          <DeleteModeBadge mode={proposedChange.deleteMode!} />
+        {/* Show new exception date for delete/single actions */}
+        {newExceptionDate && (
+          <View className="flex-row items-center mb-2">
+            <Feather
+              name="plus-circle"
+              size={16}
+              color={theme.confirmButton}
+              style={{ marginRight: 8 }}
+            />
+            <Text style={{ color: theme.confirmButton }} className="font-medium">
+              Neue Ausnahme: {formatDate(new Date(proposedChange.occurrenceDate!))}
+            </Text>
+          </View>
+        )}
+        {/* Show new UNTIL date for update actions */}
+        {newUntilDate && (
+          <View className="flex-row items-center mb-2">
+            <Feather
+              name="plus-circle"
+              size={16}
+              color={theme.confirmButton}
+              style={{ marginRight: 8 }}
+            />
+            <Text style={{ color: theme.confirmButton }} className="font-medium">
+              Neues Ende: {formatDate(newUntilDate)}
+            </Text>
+          </View>
         )}
         <ConfirmRejectButtons
           isDisabled={isDisabled}