refactor: update feed repository payload map syntax and clean up unused imports in adoption center screen

Author: afsan123

lib/repositories/feed_repository.dart

@@ -269,9 +269,9 @@ class FeedRepository {
   }) async {
     final payload = {
       'caption': caption,
-      if (location != null) 'location': location,
-      if (taggedPetIds != null) 'tagged_pet_ids': taggedPetIds,
-      if (taggedPetNames != null) 'tagged_pet_names': taggedPetNames,
+      'location': ?location,
+      'tagged_pet_ids': ?taggedPetIds,
+      'tagged_pet_names': ?taggedPetNames,
     };
 
     final data = await supabase

lib/views/adoption_center_screen.dart

@@ -3,8 +3,6 @@ import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:google_fonts/google_fonts.dart';
-import '../theme/app_theme.dart';
-import '../widgets/brand_logo.dart';
 
 class AdoptionCenterScreen extends ConsumerStatefulWidget {
   const AdoptionCenterScreen({super.key});