i18n: complete internationalization for v3.8+ features

- Add health status translations (operational, degraded, failed, circuitOpen)
- Add proxy panel translations (serviceAddress, stats, stopped state)
- Add usage filter translations (appType, statusCode, searchPlaceholder)
- Add providerIcon click hints (clickToChange, clickToSelect)
- Add config load error translations for main.tsx
- Complete Japanese proxy section (failoverQueue, autoFailover)
- Fix date/time locale in usage charts and tables
- Use t() function in all hardcoded UI strings

src/components/settings/ImportExportSection.tsx

@@ -93,7 +93,7 @@ export function ImportExportSection({
                 type="button"
                 onClick={onClear}
                 className="absolute -top-2 -right-2 h-6 w-6 rounded-full bg-red-500 hover:bg-red-600 text-white flex items-center justify-center shadow-lg transition-colors z-10"
-                aria-label="Clear selection"
+                aria-label={t("common.clear")}
               >
                 <XCircle className="h-4 w-4" />
               </button>