feat: 重构 Vision 处理架构，支持自动委托 Vision Agent

- 主 Agent 收到图片后自动检测是否支持 vision，不支持时委托 Vision Agent 处理
- 添加 qwen-ai-provider-v5 支持百炼/DashScope API
- Task 工具支持 images 参数，可传递图片给子 Agent
- Vision Agent 使用独立的 VisionConfig 配置
- 移除 UI 层的 vision fallback 逻辑，统一在 Agent 层处理
- 删除废弃的 src/utils/vision.ts（原生 fetch 实现）

package-lock.json

@@ -19,6 +19,7 @@
         "inquirer": "^12.0.0",
         "js-yaml": "^4.1.1",
         "ora": "^8.1.0",
+        "qwen-ai-provider-v5": "^1.0.2",
         "tree-sitter-bash": "^0.25.1",
         "uuid": "^13.0.0",
         "vscode-jsonrpc": "^8.2.1",
@@ -2594,6 +2595,22 @@
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       "license": "MIT"
     },
+    "node_modules/qwen-ai-provider-v5": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/qwen-ai-provider-v5/-/qwen-ai-provider-v5-1.0.2.tgz",
+      "integrity": "sha512-IMweAFhHxM2OZzeZKyDUfcxCQCLkFioQv9TkprAXttV6XeTBTSjjUc17S9dUW4rOgtWLsCXoAkaAPUHj1jQYtg==",
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@ai-sdk/provider": "^2.0.0",
+        "@ai-sdk/provider-utils": "^3.0.0"
+      },
+      "engines": {
+        "node": ">=18.0.0"
+      },
+      "peerDependencies": {
+        "zod": "^3.25.76 || ^4.1.8"
+      }
+    },
     "node_modules/resolve-pkg-maps": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/resolve-pkg-maps/-/resolve-pkg-maps-1.0.0.tgz",