Resolve all compiler warnings across daw-backend, lightningbeam-core, and
lightningbeam-editor:
- Delete dead code: the superseded CPU raster tools in raster_tool.rs
(EffectBrush/Smudge/Gradient/Transform/Warp/Liquify/Selection — replaced by
the GPU path), plus orphaned helpers and never-read struct fields.
- Mechanical fixes: drop unused imports/variables/mut, underscore unused params,
`drop(&x)` -> `let _ = x`, deprecated egui::Rounding -> CornerRadius, snake_case
rename, elided-lifetime Cow<'_, [u8]>.
- Keep the WIP CSS theming system (theme.rs/theme_render.rs) under
#[allow(dead_code)] rather than deleting it.
Editor checks warning-free; 293 core tests pass.
Color correctness:
- Unpremultiply before the sRGB OETF on the display and export blits;
encoding premultiplied color corrupted antialiased/transparent edges.
- Tag exported video as full-range BT.709 (matrix/primaries/transfer).
- Run perception effects (invert, brightness/contrast, hue/saturation)
in gamma space to match standard editors.
- Interpolate gradients in gamma space across the raster and vector paths.
- Render effect thumbnails in the same linear space as the live pipeline.
Brush performance:
- Store the raster canvas as Rgba16Float (no shadow banding from 8-bit
linear), with an incremental per-tile ping-pong sync replacing the
per-frame full-canvas copy.
- Do the linear->sRGB readback conversion on the GPU and reuse a cached
scratch texture, dropping a ~110ms-per-stroke CPU decode.
Cleanup:
- Single COLOR_WGSL prelude and shared CPU sRGB scalars instead of ~8
duplicated copies of the transfer functions.
- Shared compute-pipeline builder; smudge folded onto the tile-sync path.
Skyler Lehmkuhl