feat(account): Add category follow page

- Implemented UI for category selection
- Integrates with AccountBloc
- Shows followed categories

Author: fulleni

lib/account/view/add_category_to_follow_page.dart

@@ -0,0 +1,120 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:ht_main/account/bloc/account_bloc.dart';
+import 'package:ht_main/headlines-feed/bloc/categories_filter_bloc.dart';
+import 'package:ht_main/l10n/l10n.dart';
+import 'package:ht_main/shared/constants/app_spacing.dart';
+import 'package:ht_main/shared/widgets/widgets.dart';
+import 'package:ht_shared/ht_shared.dart';
+import 'package:ht_data_repository/ht_data_repository.dart'; // Required for HtDataRepository
+
+/// {@template add_category_to_follow_page}
+/// A page that allows users to browse and select categories to follow.
+/// {@endtemplate}
+class AddCategoryToFollowPage extends StatelessWidget {
+  /// {@macro add_category_to_follow_page}
+  const AddCategoryToFollowPage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = context.l10n;
+    // It's better to provide CategoriesFilterBloc here if it's specific to this page
+    // or ensure it's provided higher up if shared more broadly for "add" flows.
+    // For now, creating a new instance.
+    return BlocProvider(
+      create: (context) => CategoriesFilterBloc(
+        categoriesRepository: context.read<HtDataRepository<Category>>(),
+      )..add(CategoriesFilterRequested()), // Removed const
+      child: Scaffold(
+        appBar: AppBar(
+          title: Text(l10n.addCategoriesPageTitle),
+        ),
+        body: BlocBuilder<CategoriesFilterBloc, CategoriesFilterState>(
+          builder: (context, categoriesState) {
+            if (categoriesState.status == CategoriesFilterStatus.loading) {
+              return const Center(child: CircularProgressIndicator());
+            }
+            if (categoriesState.status == CategoriesFilterStatus.failure) {
+              String errorMessage = l10n.categoryFilterError;
+              if (categoriesState.error is HtHttpException) {
+                errorMessage = (categoriesState.error as HtHttpException).message;
+              } else if (categoriesState.error != null) {
+                errorMessage = categoriesState.error.toString();
+              }
+              return FailureStateWidget(
+                message: errorMessage,
+                onRetry: () => context
+                    .read<CategoriesFilterBloc>()
+                    .add(CategoriesFilterRequested()), // Removed const
+              );
+            }
+            if (categoriesState.categories.isEmpty) {
+              return FailureStateWidget(
+                message: l10n.categoryFilterEmptyHeadline,
+              ); // Re-use existing key
+            }
+
+            // Use AccountBloc to check which categories are already followed
+            return BlocBuilder<AccountBloc, AccountState>(
+              builder: (context, accountState) {
+                final followedCategories =
+                    accountState.preferences?.followedCategories ?? [];
+
+                return ListView.builder(
+                  padding: const EdgeInsets.all(AppSpacing.md),
+                  itemCount: categoriesState.categories.length,
+                  itemBuilder: (context, index) {
+                    final category = categoriesState.categories[index];
+                    final isFollowed = followedCategories
+                        .any((fc) => fc.id == category.id);
+
+                    return Card(
+                      margin: const EdgeInsets.only(bottom: AppSpacing.sm),
+                      child: ListTile(
+                        leading: category.iconUrl != null &&
+                                Uri.tryParse(category.iconUrl!)?.isAbsolute ==
+                                    true
+                            ? SizedBox(
+                                width: 36,
+                                height: 36,
+                                child: Image.network(
+                                  category.iconUrl!,
+                                  fit: BoxFit.contain,
+                                  errorBuilder:
+                                      (context, error, stackTrace) =>
+                                          const Icon(Icons.category_outlined),
+                                ),
+                              )
+                            : const Icon(Icons.category_outlined),
+                        title: Text(category.name),
+                        trailing: IconButton(
+                          icon: isFollowed
+                              ? Icon(
+                                  Icons.check_circle,
+                                  color: Theme.of(context).colorScheme.primary,
+                                )
+                              : const Icon(Icons.add_circle_outline),
+                          tooltip: isFollowed
+                              ? l10n.unfollowCategoryTooltip(category.name)
+                              : l10n.followCategoryTooltip(category.name), // New
+                          onPressed: () {
+                            context.read<AccountBloc>().add(
+                                  AccountFollowCategoryToggled(
+                                    category: category,
+                                  ),
+                                );
+                          },
+                        ),
+                        // Optional: onTap could also toggle
+                      ),
+                    );
+                  },
+                );
+              },
+            );
+          },
+        ),
+      ),
+    );
+  }
+}