feat: Implement activity management feature with Firestore integration

- Added AddActivityBottomSheet for adding custom activities to trips.
- Created Activity model to represent tourist activities.
- Developed ActivityRepository for managing activities in Firestore.
- Integrated ActivityPlacesService for searching activities via Google Places API.
- Updated ShowTripDetailsContent to navigate to activities page.
- Enhanced main.dart to include ActivityBloc and necessary repositories.

lib/blocs/activity/activity_event.dart

@@ -0,0 +1,153 @@
+import 'package:equatable/equatable.dart';
+import '../../models/activity.dart';
+
+/// Base class for all activity-related events
+abstract class ActivityEvent extends Equatable {
+  const ActivityEvent();
+
+  @override
+  List<Object?> get props => [];
+}
+
+/// Event to load activities for a specific trip
+class LoadActivities extends ActivityEvent {
+  final String tripId;
+
+  const LoadActivities(this.tripId);
+
+  @override
+  List<Object> get props => [tripId];
+}
+
+/// Event to search activities using Google Places API
+class SearchActivities extends ActivityEvent {
+  final String tripId;
+  final String destination;
+  final ActivityCategory? category;
+
+  const SearchActivities({
+    required this.tripId,
+    required this.destination,
+    this.category,
+  });
+
+  @override
+  List<Object?> get props => [tripId, destination, category];
+}
+
+/// Event to search activities by text query
+class SearchActivitiesByText extends ActivityEvent {
+  final String tripId;
+  final String destination;
+  final String query;
+
+  const SearchActivitiesByText({
+    required this.tripId,
+    required this.destination,
+    required this.query,
+  });
+
+  @override
+  List<Object> get props => [tripId, destination, query];
+}
+
+/// Event to add a single activity to the trip
+class AddActivity extends ActivityEvent {
+  final Activity activity;
+
+  const AddActivity(this.activity);
+
+  @override
+  List<Object> get props => [activity];
+}
+
+/// Event to add multiple activities at once
+class AddActivitiesBatch extends ActivityEvent {
+  final List<Activity> activities;
+
+  const AddActivitiesBatch(this.activities);
+
+  @override
+  List<Object> get props => [activities];
+}
+
+/// Event to vote for an activity
+class VoteForActivity extends ActivityEvent {
+  final String activityId;
+  final String userId;
+  final int vote; // 1 for positive, -1 for negative, 0 to remove vote
+
+  const VoteForActivity({
+    required this.activityId,
+    required this.userId,
+    required this.vote,
+  });
+
+  @override
+  List<Object> get props => [activityId, userId, vote];
+}
+
+/// Event to delete an activity
+class DeleteActivity extends ActivityEvent {
+  final String activityId;
+
+  const DeleteActivity(this.activityId);
+
+  @override
+  List<Object> get props => [activityId];
+}
+
+/// Event to filter activities
+class FilterActivities extends ActivityEvent {
+  final String? category;
+  final double? minRating;
+  final bool? showVotedOnly;
+
+  const FilterActivities({
+    this.category,
+    this.minRating,
+    this.showVotedOnly,
+  });
+
+  @override
+  List<Object?> get props => [category, minRating, showVotedOnly];
+}
+
+/// Event to refresh activities
+class RefreshActivities extends ActivityEvent {
+  final String tripId;
+
+  const RefreshActivities(this.tripId);
+
+  @override
+  List<Object> get props => [tripId];
+}
+
+/// Event to clear search results
+class ClearSearchResults extends ActivityEvent {
+  const ClearSearchResults();
+}
+
+/// Event to update activity details
+class UpdateActivity extends ActivityEvent {
+  final Activity activity;
+
+  const UpdateActivity(this.activity);
+
+  @override
+  List<Object> get props => [activity];
+}
+
+/// Event to toggle favorite status
+class ToggleActivityFavorite extends ActivityEvent {
+  final String activityId;
+  final String userId;
+
+  const ToggleActivityFavorite({
+    required this.activityId,
+    required this.userId,
+  });
+
+  @override
+  List<Object> get props => [activityId, userId];
+}