feat: add recurring event deletion with three modes

Implement three deletion modes for recurring events:
- single: exclude specific occurrence via EXDATE mechanism
- future: set RRULE UNTIL to stop future occurrences
- all: delete entire event series

Changes include:
- Add exceptionDates field to CalendarEvent model
- Add RecurringDeleteMode type and DeleteRecurringEventDTO
- EventService.deleteRecurring() with mode-based logic using rrule library
- EventController DELETE endpoint accepts mode/occurrenceDate query params
- recurrenceExpander filters out exception dates during expansion
- AI tools support deleteMode and occurrenceDate for proposed deletions
- ChatService.confirmEvent() handles recurring delete modes
- New DeleteEventModal component for unified delete confirmation UI
- Calendar screen integrates modal for both recurring and non-recurring events

packages/shared/src/models/CalendarEvent.ts

@@ -8,10 +8,18 @@ export interface CalendarEvent {
   note?: string;
   isRecurring?: boolean;
   recurrenceRule?: string;
+  exceptionDates?: string[]; // ISO date strings (YYYY-MM-DD) for excluded occurrences
   createdAt?: Date;
   updatedAt?: Date;
 }
 
+export type RecurringDeleteMode = "single" | "future" | "all";
+
+export interface DeleteRecurringEventDTO {
+  mode: RecurringDeleteMode;
+  occurrenceDate?: string; // ISO date string of the occurrence to delete
+}
+
 export interface CreateEventDTO {
   title: string;
   description?: string;
@@ -30,6 +38,7 @@ export interface UpdateEventDTO {
   note?: string;
   isRecurring?: boolean;
   recurrenceRule?: string;
+  exceptionDates?: string[];
 }
 
 export interface ExpandedEvent extends CalendarEvent {

packages/shared/src/models/ChatMessage.ts

@@ -1,4 +1,8 @@
-import { CreateEventDTO, UpdateEventDTO } from "./CalendarEvent";
+import {
+  CreateEventDTO,
+  UpdateEventDTO,
+  RecurringDeleteMode,
+} from "./CalendarEvent";
 
 export type MessageSender = "user" | "assistant";
 
@@ -13,6 +17,8 @@ export interface ProposedEventChange {
   event?: CreateEventDTO; // Required for create
   updates?: UpdateEventDTO; // Required for update
   respondedAction?: RespondedAction; // User's response to this specific proposal
+  deleteMode?: RecurringDeleteMode; // For recurring event deletion
+  occurrenceDate?: string; // ISO date string of specific occurrence for single/future delete
 }
 
 export interface ChatMessage {