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/dto/dto.go

@@ -135,6 +135,7 @@ type PostImageResponse struct {
 type PostResponse struct {
 	ID             string              `json:"id"`
 	UserID         string              `json:"user_id"`
+	ChannelID      *string             `json:"channel_id,omitempty"`
 	Title          string              `json:"title"`
 	Content        string              `json:"content"`
 	Images         []PostImageResponse `json:"images"`
@@ -159,6 +160,7 @@ type PostResponse struct {
 type PostDetailResponse struct {
 	ID             string              `json:"id"`
 	UserID         string              `json:"user_id"`
+	ChannelID      *string             `json:"channel_id,omitempty"`
 	Title          string              `json:"title"`
 	Content        string              `json:"content"`
 	Images         []PostImageResponse `json:"images"`
@@ -870,7 +872,7 @@ type GetMyMemberInfoParams struct {
 type CreateVotePostRequest struct {
 	Title       string   `json:"title" binding:"required,max=200"`
 	Content     string   `json:"content" binding:"max=2000"`
-	CommunityID string   `json:"community_id"`
+	ChannelID   *string  `json:"channel_id,omitempty"`
 	Images      []string `json:"images"`
 	VoteOptions []string `json:"vote_options" binding:"required,min=2,max=10"` // 投票选项，至少2个最多10个
 }
@@ -930,7 +932,7 @@ type AdminPostListResponse struct {
 type AdminPostDetailResponse struct {
 	ID             string              `json:"id"`
 	UserID         string              `json:"user_id"`
-	CommunityID    string              `json:"community_id"`
+	ChannelID      *string             `json:"channel_id,omitempty"`
 	Title          string              `json:"title"`
 	Content        string              `json:"content"`
 	Images         []PostImageResponse `json:"images"`