feat(library): improve performance, artwork, and preferences

[babaruh]

What and why

Improve library responsiveness and make mod metadata easier to manage.

• batch selection and enable/disable operations to reduce lag in large libraries
• improve patcher startup and status update handling
• retrieve missing mod artwork from RuneForge during import or through manual lookup
• validate and cache downloaded artwork safely
• remember library and workshop sorting, filters, searches, view settings, and expanded folders across restarts
• sort enabled mods first by default
• extend automatic detection to categorize uncategorized mods and find missing artwork while preserving successful partial results

How it was tested

• pnpm check — 309 frontend tests passed
• pnpm build
• cargo fmt --all -- --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --all-features — 459 Rust tests passed
• added tests covering bulk selection, preference persistence, enabled-first sorting, drag-and-drop behavior, Tauri commands, and automatic detection
• manually tested RuneForge artwork recovery
• tested automatic detection with missing artwork and uncategorized mods
• tested restarting the app after changing library and workshop preferences

Checklist

• Title follows Conventional Commits (feat: / fix: / docs: / chore:; ! for breaking)
• cargo fmt --all -- --check passes
• cargo clippy -- -D warnings passes
• cargo test passes
• README / docs updated if user-visible behavior changed (behavior documented above; no existing user guide covers these controls)
• Tests added for the bug fixed or feature added

[Crauzer]

I will review the PR after I'm done with the new UX migration.