Sprite-mode bake gains an additive --pixels-per-meter flag. When set,
the value is written into sprites.uv.json under atlas_meta.
pixels_per_meter. Consumers (lib-core.render path-1 via per-entity
sprite_scale) divide their project canonical px/m by this number to
auto-scale the rendered quad — atlas-native resolution no longer needs
to match the project tile-scale.
Unset (legacy bakes): atlas_meta omitted, byte-equal to v0.3.0 output.
Tests: 53/53 pass; existing buildUvJson test continues to assert the
unset-default shape.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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