feat(channel): 模型映射 + 分组搜索 + 卡片折叠 + 冲突校验

- 渠道模型映射：新增 model_mapping JSONB 字段，在账号映射之前执行
- 分组选择：添加搜索过滤 + 平台图标
- 定价卡片：支持折叠/展开，已有数据默认折叠
- 模型冲突校验：前后端均禁止同一渠道内重复模型
- 迁移 083: channels 表添加 model_mapping 列

backend/internal/repository/channel_repo.go

@@ -3,6 +3,7 @@ package repository
 import (
 	"context"
 	"database/sql"
+	"encoding/json"
 	"fmt"
 	"strings"
 
@@ -36,10 +37,14 @@ func (r *channelRepository) runInTx(ctx context.Context, fn func(tx *sql.Tx) err
 
 func (r *channelRepository) Create(ctx context.Context, channel *service.Channel) error {
 	return r.runInTx(ctx, func(tx *sql.Tx) error {
-		err := tx.QueryRowContext(ctx,
-			`INSERT INTO channels (name, description, status) VALUES ($1, $2, $3)
+		modelMappingJSON, err := marshalModelMapping(channel.ModelMapping)
+		if err != nil {
+			return err
+		}
+		err = tx.QueryRowContext(ctx,
+			`INSERT INTO channels (name, description, status, model_mapping) VALUES ($1, $2, $3, $4)
 			 RETURNING id, created_at, updated_at`,
-			channel.Name, channel.Description, channel.Status,
+			channel.Name, channel.Description, channel.Status, modelMappingJSON,
 		).Scan(&channel.ID, &channel.CreatedAt, &channel.UpdatedAt)
 		if err != nil {
 			if isUniqueViolation(err) {
@@ -68,16 +73,18 @@ func (r *channelRepository) Create(ctx context.Context, channel *service.Channel
 
 func (r *channelRepository) GetByID(ctx context.Context, id int64) (*service.Channel, error) {
 	ch := &service.Channel{}
+	var modelMappingJSON []byte
 	err := r.db.QueryRowContext(ctx,
-		`SELECT id, name, description, status, created_at, updated_at
+		`SELECT id, name, description, status, model_mapping, created_at, updated_at
 		 FROM channels WHERE id = $1`, id,
-	).Scan(&ch.ID, &ch.Name, &ch.Description, &ch.Status, &ch.CreatedAt, &ch.UpdatedAt)
+	).Scan(&ch.ID, &ch.Name, &ch.Description, &ch.Status, &modelMappingJSON, &ch.CreatedAt, &ch.UpdatedAt)
 	if err == sql.ErrNoRows {
 		return nil, service.ErrChannelNotFound
 	}
 	if err != nil {
 		return nil, fmt.Errorf("get channel: %w", err)
 	}
+	ch.ModelMapping = unmarshalModelMapping(modelMappingJSON)
 
 	groupIDs, err := r.GetGroupIDs(ctx, id)
 	if err != nil {
@@ -96,10 +103,14 @@ func (r *channelRepository) GetByID(ctx context.Context, id int64) (*service.Cha
 
 func (r *channelRepository) Update(ctx context.Context, channel *service.Channel) error {
 	return r.runInTx(ctx, func(tx *sql.Tx) error {
+		modelMappingJSON, err := marshalModelMapping(channel.ModelMapping)
+		if err != nil {
+			return err
+		}
 		result, err := tx.ExecContext(ctx,
-			`UPDATE channels SET name = $1, description = $2, status = $3, updated_at = NOW()
-			 WHERE id = $4`,
-			channel.Name, channel.Description, channel.Status, channel.ID,
+			`UPDATE channels SET name = $1, description = $2, status = $3, model_mapping = $4, updated_at = NOW()
+			 WHERE id = $5`,
+			channel.Name, channel.Description, channel.Status, modelMappingJSON, channel.ID,
 		)
 		if err != nil {
 			if isUniqueViolation(err) {
@@ -176,7 +187,7 @@ func (r *channelRepository) List(ctx context.Context, params pagination.Paginati
 
 	// 查询 channel 列表
 	dataQuery := fmt.Sprintf(
-		`SELECT c.id, c.name, c.description, c.status, c.created_at, c.updated_at
+		`SELECT c.id, c.name, c.description, c.status, c.model_mapping, c.created_at, c.updated_at
 		 FROM channels c WHERE %s ORDER BY c.id DESC LIMIT $%d OFFSET $%d`,
 		whereClause, argIdx, argIdx+1,
 	)
@@ -192,9 +203,11 @@ func (r *channelRepository) List(ctx context.Context, params pagination.Paginati
 	var channelIDs []int64
 	for rows.Next() {
 		var ch service.Channel
-		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Description, &ch.Status, &ch.CreatedAt, &ch.UpdatedAt); err != nil {
+		var modelMappingJSON []byte
+		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Description, &ch.Status, &modelMappingJSON, &ch.CreatedAt, &ch.UpdatedAt); err != nil {
 			return nil, nil, fmt.Errorf("scan channel: %w", err)
 		}
+		ch.ModelMapping = unmarshalModelMapping(modelMappingJSON)
 		channels = append(channels, ch)
 		channelIDs = append(channelIDs, ch.ID)
 	}
@@ -235,7 +248,7 @@ func (r *channelRepository) List(ctx context.Context, params pagination.Paginati
 
 func (r *channelRepository) ListAll(ctx context.Context) ([]service.Channel, error) {
 	rows, err := r.db.QueryContext(ctx,
-		`SELECT id, name, description, status, created_at, updated_at FROM channels ORDER BY id`,
+		`SELECT id, name, description, status, model_mapping, created_at, updated_at FROM channels ORDER BY id`,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("query all channels: %w", err)
@@ -246,9 +259,11 @@ func (r *channelRepository) ListAll(ctx context.Context) ([]service.Channel, err
 	var channelIDs []int64
 	for rows.Next() {
 		var ch service.Channel
-		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Description, &ch.Status, &ch.CreatedAt, &ch.UpdatedAt); err != nil {
+		var modelMappingJSON []byte
+		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Description, &ch.Status, &modelMappingJSON, &ch.CreatedAt, &ch.UpdatedAt); err != nil {
 			return nil, fmt.Errorf("scan channel: %w", err)
 		}
+		ch.ModelMapping = unmarshalModelMapping(modelMappingJSON)
 		channels = append(channels, ch)
 		channelIDs = append(channelIDs, ch.ID)
 	}
@@ -390,3 +405,27 @@ func (r *channelRepository) GetGroupsInOtherChannels(ctx context.Context, channe
 	}
 	return conflicting, nil
 }
+
+// marshalModelMapping 将 model mapping 序列化为 JSON 字节，nil/空 map 返回 '{}'
+func marshalModelMapping(m map[string]string) ([]byte, error) {
+	if len(m) == 0 {
+		return []byte("{}"), nil
+	}
+	data, err := json.Marshal(m)
+	if err != nil {
+		return nil, fmt.Errorf("marshal model_mapping: %w", err)
+	}
+	return data, nil
+}
+
+// unmarshalModelMapping 将 JSON 字节反序列化为 model mapping
+func unmarshalModelMapping(data []byte) map[string]string {
+	if len(data) == 0 {
+		return nil
+	}
+	var m map[string]string
+	if err := json.Unmarshal(data, &m); err != nil {
+		return nil
+	}
+	return m
+}