refactor(wayland): extract preference and scheduling owners

[devmobasa]

Summary

• Add PreferenceStores and RuntimeUiSlot to group onboarding, palette-recents, config-edit, and runtime-UI persistence state.
• Preserve the existing runtime-UI entry points rather than collapsing their behavior into a new facade.
• Add UiAnimationClock to own frame scheduling, deadlines, uncapped mode, and timeout calculation.
• Add FontCatalogPrewarm to own the background controller, start latch, and retry lifecycle.
• Add focused tests for animation scheduling and font-prewarm lifecycle behavior.

Stack

2 of 2. #378 is merged. Base: main.

Validation

• cargo test --workspace --all-features
• cargo test --workspace --no-default-features
• Both workspace builds and repository static checks
• cargo fmt --all -- --check
• Strict Clippy in both feature matrices reports only the known Rust 1.98 baseline diagnostics.
• Reviewed after rebase; the current tree is byte-identical to the reviewed tree.