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/components/common/user/file-manager.tsx

@@ -238,7 +238,7 @@ export function UserFileManager() {
               <Upload className='size-10' />
             </div>
             <div className='space-y-1'>
-              <h3 className='font-semibold text-sm'>{t('noFiles')}</h3>
+              <p className='font-semibold text-sm'>{t('noFiles')}</p>
               <p className='text-xs text-muted-foreground max-w-xs'>
                 {debouncedKeyword ? t('noMatchingFiles') : t('uploadFirstFile')}
               </p>