feat(channel): integrate channel functionality into post management

- Added Channel support in Post model, including ChannelID field in PostRequest and PostResponse DTOs.
- Updated PostService and PostRepository to handle channel-specific logic for creating and listing posts.
- Introduced ChannelRepository and ChannelService, along with corresponding handlers for managing channels.
- Enhanced router to include routes for channel management and public channel listing.
- Seeded default channels in the database during initialization.

internal/wire/repository.go

@@ -21,6 +21,7 @@ var RepositorySet = wire.NewSet(
 	repository.NewGroupRepository,
 	repository.NewStickerRepository,
 	repository.NewVoteRepository,
+	repository.NewChannelRepository,
 	repository.NewScheduleRepository,
 	ProvideUserActivityRepository,