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- Delete dead code: the superseded CPU raster tools in raster_tool.rs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.
Image fill is now a tab in the Fill type row rather than a separate dropdown. When
Image is active, an asset-picker combo selects which image; switching to None/Solid/
Gradient clears the image fill (it otherwise overrides them). The Image tab only
appears when there are imported image assets.
- SetImageFillAction (core): set/clear `image_fill` on the selected VectorGraph fills,
with per-fill undo (mirrors SetFillPaintAction). Image takes render priority; clearing
reveals the colour/gradient underneath.
- Info Panel Shape section: an "Image:" combo listing the document's image assets (+ None)
for the selected fill(s), showing the current assignment. Assign/clear pushes the action.
This lets an existing shape be given (or cleared of) an image fill, complementing the
import/drop placement. Next: 3.5b — persist image assets in the .beam container.
The standalone egui window didn't fit the UI. Replaced it with a collapsible
"Onion Skin" section at the bottom of the Info Panel (Enabled checkbox + frames
before/after + opacity), available regardless of selection. SharedPaneState carries
a mutable `onion_skin` ref for the controls (distinct from the gated `onion` copy
used by rendering).
Skyler Lehmkuhl