feat(broadcasts): Rich media support in backend types

- BroadcastMedia interface for image/video/gif/audio
- Extended BroadcastMetrics with media engagement tracking
- Updated CreateBroadcastSchema with media array validation

services/platform-service/src/modules/broadcasts/types.ts

@@ -68,6 +68,9 @@ export interface Broadcast {
   ctaUrl?: string;
   imageUrl?: string;
 
+  // Rich Media (multiple images/videos supported)
+  media?: BroadcastMedia[];
+
   // Targeting
   target: BroadcastTarget;
 
@@ -118,6 +121,19 @@ export interface BroadcastTarget {
   specificUserIds?: string[];
 }
 
+// Rich Media Content
+export interface BroadcastMedia {
+  type: 'image' | 'video' | 'gif' | 'audio';
+  url: string;
+  thumbnailUrl?: string;
+  width?: number;
+  height?: number;
+  duration?: number; // For video/audio in seconds
+  size?: number; // File size in bytes
+  mimeType?: string;
+}
+
+// Engagement Metrics with rich media tracking
 export interface BroadcastMetrics {
   targetedCount: number;
   sentCount: number;
@@ -126,6 +142,10 @@ export interface BroadcastMetrics {
   clickedCount: number;
   dismissedCount: number;
   convertedCount: number;
+  // Rich media engagement
+  mediaViewedCount?: number;
+  mediaCompletedCount?: number;
+  mediaClickedCount?: number;
 }
 
 // =============================================================================
@@ -172,6 +192,11 @@ export interface InAppMessage {
   bodyMarkdown?: string;
   ctaText?: string;
   ctaUrl?: string;
+  
+  // Rich Media
+  media?: BroadcastMedia[];
+  imageUrl?: string; // Legacy support
+  
   priority: 'low' | 'normal' | 'high' | 'urgent';
   style: 'banner' | 'modal' | 'toast' | 'fullscreen';
   dismissible: boolean;
@@ -221,6 +246,16 @@ export const CreateBroadcastSchema = z.object({
   ctaText: z.string().max(50).optional(),
   ctaUrl: z.string().url().max(500).optional(),
   imageUrl: z.string().url().optional(),
+  media: z.array(z.object({
+    type: z.enum(['image', 'video', 'gif', 'audio']),
+    url: z.string().url(),
+    thumbnailUrl: z.string().url().optional(),
+    width: z.number().optional(),
+    height: z.number().optional(),
+    duration: z.number().optional(),
+    size: z.number().optional(),
+    mimeType: z.string().optional(),
+  })).optional(),
   target: BroadcastTargetSchema,
   channels: z.array(z.nativeEnum(BroadcastChannel)).min(1),
   scheduledAt: z.string().datetime().optional(),