♻️ refactor(model): replace gorm.io/datatypes with JSONValue for PrefillGroup.Items; fix JSON scan across drivers

- Why:
  - Avoid introducing `gorm.io/datatypes` for a single field.
  - Align with existing pattern (`ChannelInfo`, `Properties`) using `Scanner`/`Valuer`.
  - Fix runtime error when drivers return JSON as string.

- What:
  - Introduced `JSONValue` (based on `json.RawMessage`) implementing `sql.Scanner` and `driver.Valuer`, with `MarshalJSON`/`UnmarshalJSON` to preserve raw JSON in API.
  - Updated `PrefillGroup.Items` to use `JSONValue` with `gorm:"type:json"`.
  - Localized comments in `model/prefill_group.go` to Chinese.

- Impact:
  - Resolves “unsupported Scan, storing driver.Value type string into type *json.RawMessage”.
  - Works with MySQL/Postgres/SQLite whether JSON is returned as `[]byte` or `string`.
  - API and DB schema remain unchanged; no `go.mod` changes; lints pass.

Files changed:
- model/prefill_group.go

model/prefill_group.go

@@ -2,6 +2,7 @@ package model
 
 import (
     "encoding/json"
+    "database/sql/driver"
     "one-api/common"
 
     "gorm.io/gorm"
@@ -14,11 +15,68 @@ import (
 // ["gpt-4o", "gpt-3.5-turbo"]
 // 设计遵循 3NF，避免冗余，提供灵活扩展能力。
 
+// JSONValue 基于 json.RawMessage 实现，支持从数据库的 []byte 和 string 两种类型读取
+type JSONValue json.RawMessage
+
+// Value 实现 driver.Valuer 接口，用于数据库写入
+func (j JSONValue) Value() (driver.Value, error) {
+    if j == nil {
+        return nil, nil
+    }
+    return []byte(j), nil
+}
+
+// Scan 实现 sql.Scanner 接口，兼容不同驱动返回的类型
+func (j *JSONValue) Scan(value interface{}) error {
+    switch v := value.(type) {
+    case nil:
+        *j = nil
+        return nil
+    case []byte:
+        // 拷贝底层字节，避免保留底层缓冲区
+        b := make([]byte, len(v))
+        copy(b, v)
+        *j = JSONValue(b)
+        return nil
+    case string:
+        *j = JSONValue([]byte(v))
+        return nil
+    default:
+        // 其他类型尝试序列化为 JSON
+        b, err := json.Marshal(v)
+        if err != nil {
+            return err
+        }
+        *j = JSONValue(b)
+        return nil
+    }
+}
+
+// MarshalJSON 确保在对外编码时与 json.RawMessage 行为一致
+func (j JSONValue) MarshalJSON() ([]byte, error) {
+    if j == nil {
+        return []byte("null"), nil
+    }
+    return j, nil
+}
+
+// UnmarshalJSON 确保在对外解码时与 json.RawMessage 行为一致
+func (j *JSONValue) UnmarshalJSON(data []byte) error {
+    if data == nil {
+        *j = nil
+        return nil
+    }
+    b := make([]byte, len(data))
+    copy(b, data)
+    *j = JSONValue(b)
+    return nil
+}
+
 type PrefillGroup struct {
     Id          int            `json:"id"`
     Name        string         `json:"name" gorm:"size:64;not null;uniqueIndex:uk_prefill_name,where:deleted_at IS NULL"`
     Type        string         `json:"type" gorm:"size:32;index;not null"`
-    Items       json.RawMessage `json:"items" gorm:"type:json"`
+    Items       JSONValue      `json:"items" gorm:"type:json"`
     Description string         `json:"description,omitempty" gorm:"type:varchar(255)"`
     CreatedTime int64          `json:"created_time" gorm:"bigint"`
     UpdatedTime int64          `json:"updated_time" gorm:"bigint"`