refactor: defaultTemperature/defaultTopP 从 Provider 级别迁移到 Model 级别

- 删除所有 Provider 顶层的 defaultTemperature / defaultTopP
- 为所有对话类模型添加 model 级别的推荐温度参数（基于官方文档）
- volcengine：将 extra 内温度参数提升到模型顶层正式字段
- presetDataVersion 7→8

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

compute/providers/dashscope.json

@@ -22,8 +22,6 @@
     "omni",
     "translation"
   ],
-  "defaultTemperature": 0.7,
-  "defaultTopP": 0.8,
   "models": [
     {
       "modelName": "qwen3.5-plus",
@@ -44,6 +42,8 @@
       ],
       "inputPrice": 0.8,
       "outputPrice": 4.8,
+      "defaultTemperature": 0.7,
+      "defaultTopP": 0.8,
       "extra": {}
     },
     {
@@ -62,6 +62,8 @@
       ],
       "inputPrice": 2.4,
       "outputPrice": 9.6,
+      "defaultTemperature": 0.7,
+      "defaultTopP": 0.8,
       "extra": {}
     },
     {
@@ -79,6 +81,8 @@
       ],
       "inputPrice": 0.8,
       "outputPrice": 2,
+      "defaultTemperature": 0.6,
+      "defaultTopP": 0.8,
       "extra": {}
     },
     {
@@ -95,6 +99,8 @@
       ],
       "inputPrice": 0.3,
       "outputPrice": 0.6,
+      "defaultTemperature": 0.7,
+      "defaultTopP": 0.8,
       "extra": {}
     },
     {
@@ -111,6 +117,8 @@
       ],
       "inputPrice": 0.5,
       "outputPrice": 2,
+      "defaultTemperature": 0.7,
+      "defaultTopP": 0.8,
       "extra": {}
     },
     {
@@ -131,6 +139,8 @@
       ],
       "inputPrice": 2.5,
       "outputPrice": 10,
+      "defaultTemperature": 0.7,
+      "defaultTopP": 0.8,
       "extra": {}
     },
     {