feat: add EditEventScreen with calendar and chat mode support

Add a unified event editor that works in two modes:
- Calendar mode: Create/edit events directly via EventService API
- Chat mode: Edit AI-proposed events before confirming them

The chat mode allows users to modify proposed events (title, time,
recurrence) and persists changes both locally and to the server.

New components: DateTimePicker, ScrollableDropdown, useDropdownPosition
New API: PUT /api/chat/messages/:messageId/proposal

apps/server/src/repositories/mongo/MongoChatRepository.ts

@@ -2,6 +2,7 @@ import {
   ChatMessage,
   Conversation,
   CreateMessageDTO,
+  CreateEventDTO,
   GetMessagesOptions,
   UpdateMessageDTO,
 } from "@calchat/shared";
@@ -82,4 +83,17 @@ export class MongoChatRepository implements ChatRepository {
     );
     return doc ? (doc.toJSON() as unknown as ChatMessage) : null;
   }
+
+  async updateProposalEvent(
+    messageId: string,
+    proposalId: string,
+    event: CreateEventDTO,
+  ): Promise<ChatMessage | null> {
+    const doc = await ChatMessageModel.findOneAndUpdate(
+      { _id: messageId, "proposedChanges.id": proposalId },
+      { $set: { "proposedChanges.$.event": event } },
+      { new: true },
+    );
+    return doc ? (doc.toJSON() as unknown as ChatMessage) : null;
+  }
 }

apps/server/src/repositories/mongo/models/ChatModel.ts

@@ -23,7 +23,6 @@ const EventSchema = new Schema<CreateEventDTO>(
     startTime: { type: Date, required: true },
     endTime: { type: Date, required: true },
     note: { type: String },
-    isRecurring: { type: Boolean },
     recurrenceRule: { type: String },
     exceptionDates: { type: [String] },
   },
@@ -37,7 +36,6 @@ const UpdatesSchema = new Schema<UpdateEventDTO>(
     startTime: { type: Date },
     endTime: { type: Date },
     note: { type: String },
-    isRecurring: { type: Boolean },
     recurrenceRule: { type: String },
   },
   { _id: false },

apps/server/src/repositories/mongo/models/EventModel.ts

@@ -2,16 +2,22 @@ import mongoose, { Schema, Document, Model } from "mongoose";
 import { CalendarEvent } from "@calchat/shared";
 import { IdVirtual } from "./types";
 
-export interface EventDocument extends Omit<CalendarEvent, "id">, Document {
+interface EventVirtuals extends IdVirtual {
+  isRecurring: boolean;
+}
+
+export interface EventDocument
+  extends Omit<CalendarEvent, "id" | "isRecurring">,
+    Document {
   toJSON(): CalendarEvent;
 }
 
 const EventSchema = new Schema<
   EventDocument,
-  Model<EventDocument, {}, {}, IdVirtual>,
+  Model<EventDocument, {}, {}, EventVirtuals>,
   {},
   {},
-  IdVirtual
+  EventVirtuals
 >(
   {
     userId: {
@@ -39,10 +45,6 @@ const EventSchema = new Schema<
     note: {
       type: String,
     },
-    isRecurring: {
-      type: Boolean,
-      default: false,
-    },
     recurrenceRule: {
       type: String,
     },
@@ -59,6 +61,11 @@ const EventSchema = new Schema<
           return this._id.toString();
         },
       },
+      isRecurring: {
+        get() {
+          return !!this.recurrenceRule;
+        },
+      },
     },
     toJSON: {
       virtuals: true,