v0.0.6

Other

• replace never-match regex with semver_check = false
• migrate to centralized OxideAV/.github reusable workflows
• add YUV4MPEG2 demuxer + muxer
• drop unused PcmDecoder.sample_rate field (slim-frame leftover)
• adopt slim AudioFrame shape
• pin release-plz to patch-only bumps

Added

• Y4M (YUV4MPEG2) raw-video demuxer + muxer (y4m module). Handles
  4:2:0 / 4:2:2 / 4:4:4 / mono at 8/10/12-bit, preserves header
  X<key>=<val> extensions in Demuxer::metadata, and probes on the
  YUV4MPEG2 magic. Frames are emitted as rawvideo packets.