gui_toolkit 0.38.0

Added

• Native text backend (-define:FONT_BACKEND=native, font/backend_native.odin, native/text, tools/build_text.ps1): Fontations (read-fonts' font model), HarfRust and ICU4X (line breaks with dictionaries, bidi through unicode-bidi) in a static Rust library behind a C ABI, built and pinned like Wren's image decoders. Shapes 2.6 times faster than DirectWrite on the corpus (2.0 ┬Ás a word against 5.2, without the word cache). Faces are still opened by the platform; Settings.backend picks either backend for one State. font.native_table, font.native_coverage, font.native_outline_provider. See docs/font-backend.md.
• tools/text_bench and tests/text_backends: the two backends compared on the corpus (equivalence report and timings; logic checks in the tests).

Changed

• The font package compiles on Linux and macOS (odin check font -target:linux_amd64 / darwin_arm64): DirectWrite and Direct2D are behind font_windows.odin, raster_windows.odin and the color files; font_other.odin loads faces from files and memory through the native backend (no system fonts yet: TODO fontconfig / CoreText). load_memory takes font.Simulations ({.Bold, .Oblique}) instead of DirectWrite's flags.

Fixed

• Kerning under letter-spacing and font-feature-settings (dwrite backend): an explicit feature list replaced DirectWrite's default features (kern, liga, clig, calt, rclt); they are now kept unless the list sets them.
• tests/retained passes with FONT_TEXT_RENDERER=slug too (its atlas page assertions follow the renderer).