Add Audio Processing Templates management UI to Streams tab:
- Template editor modal with filter list via FilterListManager
- CardSection with reconciliation for template cards
- DataCache instances for templates and audio filter defs
- Audio filter icon mappings in filter-list.ts
- i18n keys in en/ru/zh locales
Add the foundation for audio processing filters, mirroring the existing
picture filter/postprocessing template system:
- AudioFilter base class, AudioFilterRegistry, AudioFilterOptionDef
- AudioProcessingTemplate dataclass + SQLite-backed store
- audio_filter_template meta-filter with recursive resolution
- Full REST API: CRUD templates + filter registry discovery
- Dependency injection wired in dependencies.py and main.py
alexei.dolgolyov