chore(#5499): drop redundant post-divider _applyVoiceModePref call

The success branch had two adjacent calls:

  if(typeof window._applyVoiceModePref==='function') window._applyVoiceModePref();   // pre-divider (the actual fix)
  _applyComposerFooterVisibilitySettings();
  if(typeof window._applyVoiceModePref==='function') window._applyVoiceModePref();   // post-divider (redundant)

The post-divider one ran after _applyComposerFooterVisibilitySettings,
so it couldn't affect the divider the PR was meant to fix. It looked
like a defensive double-tap, but the function is idempotent and the
pref source (localStorage) doesn't change between the two synchronous
calls — so it was just dead code that made the diff look bigger than
the actual semantic change.

Drop it. Net PR footprint is now strictly: 'use the window-qualified
name and apply once before divider recompute in both IIFE branches.'

Re-tested: 26/26 pass on test_issue4598_composer_control_visibility
+ test_issue1488_composer_voice_buttons.

static/boot.js

@@ -2998,7 +2998,6 @@ window._mirrorSpeechSettingsFromServer=_mirrorSpeechSettingsFromServer;
     // closure-local to the voice-mode IIFE and not visible here.
     if(typeof window._applyVoiceModePref==='function') window._applyVoiceModePref();
     _applyComposerFooterVisibilitySettings();
-    if(typeof window._applyVoiceModePref==='function') window._applyVoiceModePref();
     // TTS: apply enabled state on boot so buttons show/hide correctly (#499)
     if(typeof _applyTtsEnabled==='function') _applyTtsEnabled(localStorage.getItem('hermes-tts-enabled')==='true');
   }catch(e){