feat: add video conference meeting link generation to event modal

- Add video conference utility functions for generating random meeting IDs
- Implement video meeting button with camera icon in EventModal
- Add copy and delete functionality with IconButton components
- Support X-OPENPAAS-VIDEOCONFERENCE field in CalendarEvent type
- Handle state management for editing events with/without video conference
- Add meeting link footer to event description
- Include comprehensive test suite for video conference utilities

Features:
- Generate random meeting links (format: xxx-xxxx-xxx)
- Copy meeting link to clipboard
- Remove video conference from events
- Proper state sync when editing different events
- Integration with existing JCal/ICS conversion

src/utils/__test__/videoConferenceUtils.test.ts

@@ -0,0 +1,65 @@
+import { generateMeetingId, generateMeetingLink, addVideoConferenceToDescription, extractVideoConferenceFromDescription } from '../videoConferenceUtils';
+
+describe('videoConferenceUtils', () => {
+  describe('generateMeetingId', () => {
+    it('should generate meeting ID in correct format', () => {
+      const meetingId = generateMeetingId();
+      expect(meetingId).toMatch(/^[a-z]{3}-[a-z]{4}-[a-z]{3}$/);
+    });
+
+    it('should generate different IDs each time', () => {
+      const id1 = generateMeetingId();
+      const id2 = generateMeetingId();
+      expect(id1).not.toBe(id2);
+    });
+  });
+
+  describe('generateMeetingLink', () => {
+    it('should generate link with default base URL', () => {
+      const link = generateMeetingLink();
+      expect(link).toMatch(/^https:\/\/meet\.linagora\.com\/[a-z]{3}-[a-z]{4}-[a-z]{3}$/);
+    });
+
+    it('should generate link with custom base URL', () => {
+      const customBase = 'https://custom-meet.example.com';
+      const link = generateMeetingLink(customBase);
+      expect(link).toMatch(/^https:\/\/custom-meet\.example\.com\/[a-z]{3}-[a-z]{4}-[a-z]{3}$/);
+    });
+  });
+
+  describe('addVideoConferenceToDescription', () => {
+    it('should add video conference footer to empty description', () => {
+      const description = '';
+      const meetingLink = 'https://meet.linagora.com/abc-defg-hij';
+      const result = addVideoConferenceToDescription(description, meetingLink);
+      expect(result).toBe('\n\nVisio: https://meet.linagora.com/abc-defg-hij');
+    });
+
+    it('should add video conference footer to existing description', () => {
+      const description = 'This is a meeting description.';
+      const meetingLink = 'https://meet.linagora.com/abc-defg-hij';
+      const result = addVideoConferenceToDescription(description, meetingLink);
+      expect(result).toBe('This is a meeting description.\n\nVisio: https://meet.linagora.com/abc-defg-hij');
+    });
+  });
+
+  describe('extractVideoConferenceFromDescription', () => {
+    it('should extract video conference link from description', () => {
+      const description = 'Meeting description.\n\nVisio: https://meet.linagora.com/abc-defg-hij';
+      const result = extractVideoConferenceFromDescription(description);
+      expect(result).toBe('https://meet.linagora.com/abc-defg-hij');
+    });
+
+    it('should return null when no video conference link found', () => {
+      const description = 'Just a regular meeting description.';
+      const result = extractVideoConferenceFromDescription(description);
+      expect(result).toBeNull();
+    });
+
+    it('should return null for empty description', () => {
+      const description = '';
+      const result = extractVideoConferenceFromDescription(description);
+      expect(result).toBeNull();
+    });
+  });
+});