fix(pitch-deck): presenter fixes — prev button, TTS pronunciation, text accuracy

- Fix: Zurück-Button — onPrev was not passed to PresenterOverlay
- TTS: BreakPilot, Executive Summary etc. pronounced in English
- "Ihre Kunden" → "Unsere Kunden"
- "kein kleine" → "kein kleines und mittleres Unternehmen vorhalten kann"
- Removed all false "lösen/befreien" claims

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pitch-deck/components/PitchDeck.tsx

@@ -282,6 +282,7 @@ export default function PitchDeck({ lang, onToggleLanguage, investor, onLogout,
         onResume={presenter.resume}
         onStop={presenter.stop}
         onSkip={presenter.skipSlide}
+        onPrev={presenter.prevSlide}
       />
 
       <AnimatePresence>