fix(i18n): deduplicate category labels by reusing providerForm keys

- Change ProviderForm to use providerForm.category* instead of providerPreset.category*
- Remove duplicate category keys from providerPreset namespace in both zh.json and en.json
- Fix naming inconsistency: use categoryAggregation (not categoryAggregator)
- Fixes issue where English UI would show Chinese defaultValue fallbacks

This ensures single source of truth for category labels and improves maintainability.

src/i18n/locales/zh.json

@@ -343,6 +343,16 @@
     "configPreview": "配置预览",
     "applyConfig": "应用配置"
   },
+  "geminiConfig": {
+    "envFile": "环境变量 (.env)",
+    "envFileHint": "使用 .env 格式配置 Gemini 环境变量",
+    "configJson": "配置文件 (config.json)",
+    "configJsonHint": "使用 JSON 格式配置 Gemini 扩展参数（可选）",
+    "writeCommonConfig": "写入通用配置",
+    "editCommonConfig": "编辑通用配置",
+    "editCommonConfigTitle": "编辑 Gemini 通用配置片段",
+    "commonConfigHint": "通用配置片段将合并到所有启用它的 Gemini 供应商配置中"
+  },
   "providerPreset": {
     "label": "预设供应商",
     "custom": "自定义配置",