fix(frontend): make the panel usable with screen readers (#6907)

* fix(frontend): make the panel usable with screen readers

* fix(frontend): keep mobile tab names and the inbound expiry hint

Review of #6907 found two gaps in the screen-reader pass:

- On phone-width screens catTabLabel renders only the icon and names the
  tab by putting aria-label on it, but callers now pass that icon with
  aria-hidden for the desktop label, so every Settings, Xray and Host
  category tab lost its name under TalkBack. catTabLabel now clears
  aria-hidden on the icon it uses as the name.
- DateTimePicker forwarded id and aria-label but not aria-describedby,
  so the inbound expiry hint ("leave blank to never expire") was never
  attached. It now forwards it on both the Gregorian and Jalali input.

frontend/src/components/feedback/TextModal.tsx

@@ -69,11 +69,11 @@ export default function TextModal({
         footer={
           <>
             {fileName && (
-              <Button icon={<DownloadOutlined />} onClick={download}>
+              <Button icon={<DownloadOutlined aria-hidden />} onClick={download}>
                 {fileName}
               </Button>
             )}
-            <Button type="primary" icon={<CopyOutlined />} onClick={copy}>
+            <Button type="primary" icon={<CopyOutlined aria-hidden />} onClick={copy}>
               {t('copy')}
             </Button>
           </>