### Standard

- `SPEC.md` rewritten as a capability-menu spec. Mandatory floor:
  `wai.image.png`, `wai.audio.flac`, `wai.text.zstd` (every conforming
  sink MUST decode these). Recommended modern set: `wai.image.jxl`,
  `wai.image.avif`, `wai.image.jpeg`, `wai.audio.opus`, `wai.video.av1`,
  `wai.video.av1.lossless`, `wai.text.xz`. Neural capabilities
  (`wai.neural.*`) remain OPTIONAL and sink-advertised.
- Container envelope (`WAI1` magic + length-prefixed manifest + length-
  prefixed payload) and manifest schema are unchanged from v0.2.x.
- Conformance: bit-exact decode-equivalence with each capability's
  reference library (libjxl / libavif / libopus / libFLAC / rav1e / etc.).

