refactor: improve AI event handling and conflict display in chat

- AI fetches events on-demand via callbacks for better efficiency
- Add conflict detection with warning display when proposing overlapping events
- Improve event search and display in chat interface
- Load full chat history for display while limiting AI context

apps/client/src/components/ProposedEventCard.tsx

@@ -1,6 +1,6 @@
 import { View, Text, Pressable } from "react-native";
-import { Feather } from "@expo/vector-icons";
-import { ProposedEventChange, formatDate } from "@calchat/shared";
+import { Feather, Ionicons } from "@expo/vector-icons";
+import { ProposedEventChange, formatDate, formatTime } from "@calchat/shared";
 import { rrulestr } from "rrule";
 import { useThemeStore } from "../stores/ThemeStore";
 import { EventCardBase } from "./EventCardBase";
@@ -143,6 +143,29 @@ export const ProposedEventCard = ({
             </Text>
           </View>
         )}
+        {/* Show conflicting events warning */}
+        {proposedChange.conflictingEvents &&
+          proposedChange.conflictingEvents.length > 0 && (
+            <View className="mb-2">
+              {proposedChange.conflictingEvents.map((conflict, index) => (
+                <View key={index} className="flex-row items-center mt-1">
+                  <Ionicons
+                    name="alert-circle"
+                    size={16}
+                    color={theme.rejectButton}
+                    style={{ marginRight: 8 }}
+                  />
+                  <Text
+                    style={{ color: theme.rejectButton }}
+                    className="text-sm flex-1"
+                  >
+                    Konflikt: {conflict.title} ({formatTime(conflict.startTime)}{" "}
+                    - {formatTime(conflict.endTime)})
+                  </Text>
+                </View>
+              ))}
+            </View>
+          )}
         <ActionButtons
           isDisabled={isDisabled}
           respondedAction={proposedChange.respondedAction}