Korean vocabulary, TOPIK words

- Made auto-advance behavior and the answer info layout consistent on the answer panel. - Fixed example-based quizzes so the speaker reads the example sentence instead of the word. - Polished example pronunciation to sound like a single, natural utterance and resolved partial cut-offs in playback. - Fixed a crash when entering the unit screen via an unintended route. - Mitigated an iOS crash where a network-status callback reached a torn-down engine when the app moved to the background. - Hardened against rare crashes in speech recognition, pronunciation, ads, and drag interactions.