Merge branch 'main' into lucas/malmal/main

Re-port the WASM canvas font fallback onto main's new skrifa/harfrust
shaping pipeline:
- Add `chr` to `ShapedGlyph` and trigger the canvas fallback from
  `allocate_glyph` on NOTDEF (WASM only).
- Drive the fallback from `text_layout`'s NOTDEF branch via `has_glyph`,
  so it only kicks in when no loaded font contains the character.
- Update `allocate_canvas_glyph` for main's `GlyphAllocation` (uv_rect
  only) and `color_transfer_function` API; fix `get_image_data` f64 args.

Merge the per-axis scroll fade gating into main's refactored
`paint_fade_areas_impl`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/epaint/Cargo.toml

@@ -48,7 +48,14 @@ mint = ["emath/mint"]
 rayon = ["dep:rayon"]
 
 ## Allow serialization using [`serde`](https://docs.rs/serde).
-serde = ["dep:serde", "ahash/serde", "emath/serde", "ecolor/serde", "font-types/serde", "smallvec/serde"]
+serde = [
+  "dep:serde",
+  "ahash/serde",
+  "ecolor/serde",
+  "emath/serde",
+  "font-types/serde",
+  "smallvec/serde",
+]
 
 ## Change Vertex layout to be compatible with unity
 unity = []
@@ -63,6 +70,7 @@ ecolor.workspace = true
 
 ahash.workspace = true
 font-types.workspace = true
+harfrust.workspace = true
 log.workspace = true
 nohash-hasher.workspace = true
 parking_lot.workspace = true # Using parking_lot over std::sync::Mutex gives 50% speedups in some real-world scenarios.
@@ -70,6 +78,8 @@ profiling.workspace = true
 self_cell.workspace = true
 skrifa.workspace = true
 smallvec.workspace = true
+unicode-general-category.workspace = true
+unicode-segmentation.workspace = true
 vello_cpu.workspace = true
 
 #! ### Optional dependencies