i18n: complete internationalization for provider and usage query panels

- Add 45+ new translation keys for usage query and usage script features
- Fix duplicate provider object in translation files that caused missing translations
- Remove all hardcoded Chinese text and defaultValue fallbacks from components
- Add proper translations for:
  * Usage footer (query status, plan usage display)
  * Usage script modal (script editor, validation, test controls)
  * Provider forms (basic fields, endpoints, model selectors)
  * Provider dialogs (add/edit hints and titles)

Modified 16 files:
- 2 translation files (zh.json, en.json)
- 14 component files (removed defaultValue, added t() calls)

All UI text now properly supports Chinese/English switching.

src/components/providers/forms/ProviderForm.tsx

@@ -554,7 +554,7 @@ export function ProviderForm({
         {showButtons && (
           <div className="flex justify-end gap-2">
             <Button variant="outline" type="button" onClick={onCancel}>
-              {t("common.cancel", { defaultValue: "取消" })}
+              {t("common.cancel")}
             </Button>
             <Button type="submit">{submitLabel}</Button>
           </div>