v0.1.6

Other

• drop stale REGISTRARS / with_all_features intra-doc links
• drop dead linkme dep
• re-export __oxideav_entry from registry sub-module
• add SA progressive + metadata pass-through API
• auto-register via oxideav_core::register! macro (linkme distributed slice)

Added

• encode_jpeg_progressive_sa / encode_jpeg_progressive_sa_with_meta: full
  successive-approximation (SA) progressive JPEG encoder using a 1-bit point
  transform (Al=1 initial, Ah=1,Al=0 refinement). Produces 14 SOS scans
  (1 DC initial + 6 AC initial + 1 DC refine + 6 AC refine) that round-trip
  through ffmpeg, libjpeg, and ImageMagick with PSNR ≥ 40 dB relative to the
  source. Implements T.81 §G.1.2.3 AC refinement with correction bits
  interleaved inline during the decoder's zero-history walk.
• encode_jpeg_with_meta / encode_jpeg_progressive_with_meta: variants of
  the baseline and spectral-selection progressive encoders that accept a meta
  byte slice of pre-serialised APP0-APP15 and COM segments to embed verbatim,
  replacing the default JFIF APP0 marker.
• extract_app_segments(jpeg: &[u8]) -> Vec<u8>: walks a JPEG byte stream and
  returns a contiguous buffer of all APP (0xFF 0xEn) and COM (0xFF 0xFE)
  segment bytes, ready to pass as meta to the *_with_meta encoder family.