feat: Add RNNoise denoising + transient suppressor + VAD improvements

- Add RNNoise neural network audio denoising (16kHz↔48kHz resampling)
- Add transient suppressor to filter claps/clicks/pops before RNNoise
- VAD now works on FILTERED audio (not raw) to avoid false triggers
- Real-time denoised audio level display in UI
- Save denoised audio previews in Opus format (.ogg)
- Add extensive Whisper hallucination filter (Tingting, music, etc.)
- Add "Clear" button to reset accumulated translations
- Double VAD thresholds (0.02/0.08) for less sensitivity
- Update Claude prompt to handle offensive content gracefully

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/main_console.cpp

@@ -41,13 +41,12 @@ int main() {
     }
     std::cout << "      ✓ Configuration loaded" << std::endl;
 
-    // Initialize audio
+    // Initialize audio with VAD-based segmentation
     std::cout << "[2/4] Initializing audio capture..." << std::endl;
     auto& audio_cfg = config.getAudioConfig();
     secondvoice::AudioCapture audio(
         audio_cfg.sample_rate,
-        audio_cfg.channels,
+        audio_cfg.channels
-        audio_cfg.chunk_duration_seconds
     );
 
     if (!audio.initialize()) {