docs: document EvolutionGroup type with API response format

src/services/group-sync.ts

@@ -5,11 +5,31 @@ const env = process.env;
 // In-memory cache for active groups
 const activeGroupsCache = new Map<string, string>(); // groupId -> groupName
 
+/**
+ * Represents a group from the Evolution API response
+ * 
+ * API returns an array of groups in this format:
+ * [
+ *   {
+ *     id: string,          // Group ID in @g.us format (primary key)
+ *     subject: string,     // Group name (displayed to users)
+ *     linkedParent?: string, // Parent community ID if group belongs to one
+ *     size?: number,       // Current member count (unused in our system)
+ *     creation?: number,   // Unix timestamp of group creation (unused)
+ *     desc?: string,       // Group description text (unused)
+ *     // ...other fields exist but are ignored by our implementation
+ *   }
+ * ]
+ * 
+ * Required fields for our implementation:
+ * - id (used as database primary key)
+ * - subject (used as group display name)
+ * - linkedParent (used for community filtering)
+ */
 type EvolutionGroup = {
 	id: string;
 	subject: string;
 	linkedParent?: string;
-	// Other fields from API response
 };
 
 export class GroupSyncService {