- Add `get_dimensions()` method to VideoFromFile fallback class across all vidu and wan_ai modules
- Implement PyAV (av) library integration to extract video width and height from container streams
- Add dimension caching with `_width` and `_height` attributes to avoid redundant parsing
- Implement fallback dimensions (1280x720) when video parsing fails
- Add proper stream seeking to reset file position after dimension extraction
- Update requirements.txt to include av library dependency
- Ensure consistent video dimension handling across vidu_t2v, vidu_i2v, vidu_ref2v, vidu_startend2v, vidu_extend, wan_ai_t2v, and wan_ai_i2v modules