- Add CENC namespace support for kid/default_KID attributes
- Detect and replace placeholder/test KIDs in Widevine PSSH:
- All zeros (key rotation default)
- Sequential 0x00-0x0f pattern
- Shaka Packager test pattern
- Change DRM init condition from `not track.drm` to `init_data` to ensure DRM is always re-initialized from init segments
Fixes issue where Widevine PSSH contains placeholder KIDs while the real KID is only in ContentProtection default_KID attributes.