* PNG: keep a stereo file's sTER pairing on save (#6063)
Read the sTER chunk (PNG Extensions 1.4.0 §3.6) when a PNG opens, store it
on the document's FileEncoding, and write it back when saving, so a stereo
PNG still says it is a stereo pair. Covers the ordinary and the palette
PNG encoders, including interlaced output.
* io tests: pass the new sTER argument to encode_png_indexed
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: highperfocused <highperfocused@pm.me>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
The palette PNG encoder never wrote a pHYs chunk, so an Indexed Color
document saved as PNG reopened at 72 ppi while the RGB path kept its
resolution. encode_png_indexed now takes an optional dpi and the flat
exporter passes the document resolution under the same embed_metadata
rule as the ordinary PNG encoder. Save for Web PNG-8 is unchanged.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
CI's `cargo fmt --all -- --check` has failed on every run because the
repo had no rustfmt config and was never formatted. Use the same settings
as EffectCraft/FilmCraft (max_width 160, use_small_heuristics Max), which
also keeps the churn small. Formatting only; no code changes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
