[twill-iced] Migrate to iced_core and iced_widgets

[T-256]

Main motivation here is to avoid enabling extra features of iced, then turns out it could be removed in favor of its underlying crates.

I test this PR via my own app that uses iced-shadcn->twill-iced.

[T-256]

Thanks for merge, the main reason I removed wgpu feature was because I only need to compile with tiny-skia for compability and binary size. now 16c8afb prevent me to do such thing.

[FerrisMind]

Thanks for reporting this and for your interest in this project — you were right. Hard-coding WGPU broke Tiny Skia-only builds.

I’ve updated the feature model:

• twill-iced now enables WGPU and Tiny Skia by default, with WGPU as the primary renderer and Tiny Skia as fallback;
• the facade feature iced enables both renderers;
• iwgpu enables only WGPU;
• itskia enables only Tiny Skia.

For a direct twill-iced dependency, use:

twill-iced = {
    version = "0.3",
    default-features = false,
    features = ["tiny-skia"]
}

I verified that the itskia dependency graph does not include iced_wgpu, and all three configurations build successfully. Could you please test the Tiny Skia-only setup in your project?

You need to update to commit 9d2f2a4