a11y 收尾：主题级对比度根因修复（indigo-500→600）+12 处控件 accessible name+4 处 heading-order，7 页复扫全 0 违规；基准 total_issues 保持 8

Result: {"status":"keep","total_issues":8,"eslint_errors":0,"eslint_problems":0,"eslint_warnings":0,"golint_canonicalheader":0,"golint_errname":0,"golint_errorlint":1,"golint_exhaustive":0,"golint_forcetypeassert":0,"golint_gosec":0,"golint_intrange":0,"golint_modernize":3,"golint_nilnil":3,"golint_perfsprint":0,"golint_prealloc":0,"golint_recvcheck":1,"golint_test_testifylint":0,"golint_test_thelper":0,"golint_test_total":0,"golint_test_usetesting":0,"golint_total":8,"golint_usestdlibvars":0,"golint_vetx_total":0,"golint_wastedassign":0,"measure_s":85,"tsc_errors":0,"vitest_failed":0,"vitest_total":126}

frontend/app/(main)/admin/database/components/table-browser.tsx

@@ -140,7 +140,7 @@ export function TableBrowser({
             <Skeleton className='h-8 w-48' />
           ) : (
             <Select value={selectedTable} onValueChange={handleTableChange}>
-              <SelectTrigger className='h-8 w-[200px] text-xs bg-background border-border/40'>
+              <SelectTrigger aria-label={t('selectTable')} className='h-8 w-[200px] text-xs bg-background border-border/40'>
                 <SelectValue placeholder={t('selectTable')} />
               </SelectTrigger>
               <SelectContent className='max-h-[300px]'>