chore(i18n): add translations for icon picker and provider icon

Add Chinese and English translations for icon customization feature:

## Icon Picker (iconPicker)
- search: "Search Icons" / "搜索图标"
- searchPlaceholder: "Enter icon name..." / "输入图标名称..."
- noResults: "No matching icons found" / "未找到匹配的图标"
- category.aiProvider: "AI Providers" / "AI 服务商"
- category.cloud: "Cloud Platforms" / "云平台"
- category.tool: "Dev Tools" / "开发工具"
- category.other: "Other" / "其他"

## Provider Icon (providerIcon)
- label: "Icon" / "图标"
- colorLabel: "Icon Color" / "图标颜色"
- selectIcon: "Select Icon" / "选择图标"
- preview: "Preview" / "预览"

These translations support the new icon picker UI components
and provider form icon selection interface.

src/i18n/locales/en.json

@@ -726,5 +726,22 @@
     "importSuccess": "Import successful",
     "importSuccessDescription": "Provider \"{{name}}\" has been successfully imported",
     "importError": "Failed to import"
+  },
+  "iconPicker": {
+    "search": "Search Icons",
+    "searchPlaceholder": "Enter icon name...",
+    "noResults": "No matching icons found",
+    "category": {
+      "aiProvider": "AI Providers",
+      "cloud": "Cloud Platforms",
+      "tool": "Dev Tools",
+      "other": "Other"
+    }
+  },
+  "providerIcon": {
+    "label": "Icon",
+    "colorLabel": "Icon Color",
+    "selectIcon": "Select Icon",
+    "preview": "Preview"
   }
 }

src/i18n/locales/zh.json

@@ -726,5 +726,22 @@
     "importSuccess": "导入成功",
     "importSuccessDescription": "供应商 \"{{name}}\" 已成功导入",
     "importError": "导入失败"
+  },
+  "iconPicker": {
+    "search": "搜索图标",
+    "searchPlaceholder": "输入图标名称...",
+    "noResults": "未找到匹配的图标",
+    "category": {
+      "aiProvider": "AI 服务商",
+      "cloud": "云平台",
+      "tool": "开发工具",
+      "other": "其他"
+    }
+  },
+  "providerIcon": {
+    "label": "图标",
+    "colorLabel": "图标颜色",
+    "selectIcon": "选择图标",
+    "preview": "预览"
   }
 }