feat: complete Phase 11.4 - comprehensive audio file import
Implemented advanced audio import capabilities:
**Import Features:**
- Support for WAV, MP3, OGG, FLAC, M4A, AIFF formats
- Sample rate conversion using OfflineAudioContext
- Stereo to mono conversion (equal channel mixing)
- Normalize on import option (99% peak with 1% headroom)
- Comprehensive codec detection from MIME types and extensions
**API Enhancements:**
- ImportOptions interface (convertToMono, targetSampleRate, normalizeOnImport)
- importAudioFile() function returning buffer + metadata
- AudioFileInfo with AudioMetadata (codec, duration, channels, sample rate, file size)
- Enhanced decodeAudioFile() with optional import transformations
**UI Components:**
- ImportDialog component with import settings controls
- Sample rate selector (44.1kHz - 192kHz)
- Checkbox options for mono conversion and normalization
- File info display (original sample rate and channels)
- Updated FileUpload to show AIFF support
**Technical Implementation:**
- Offline resampling for quality preservation
- Equal-power channel mixing for stereo-to-mono
- Peak detection across all channels
- Metadata extraction with codec identification
Phase 11 (Export & Import) now complete!
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
Sebastian Krüger
37f910acb7