feat: add mobile TOC animation

[powerfullz]

This pull request refactors and enhances the mobile slide animation logic for both the main menu and the article Table of Contents (TOC). It introduces a shared animation module, improves accessibility and responsiveness, and updates related styles for a smoother user experience, especially on mobile devices.

Shared Slide Animation Core:

• Introduced a new slideAnimation.ts module that centralizes slide open/close logic, ensuring consistent and accessible animations for both the mobile menu and TOC. The implementation includes reduced-motion support, transition lifecycle handling, and inline style cleanup.

Mobile Menu Refactor:

• Refactored menu.ts to use the new shared slide animation utilities, replacing the legacy slideUp/slideDown code. The menu now respects reduced-motion settings, handles animation state more robustly, and ensures the menu closes cleanly on window resize.

Mobile TOC Animation:

• Added a new mobileToc.ts module that applies the shared slide animation logic to the article TOC. This enables smooth expand/collapse behavior for the TOC on mobile, with proper handling of animation state, reduced-motion, and window resizes.
• Integrated the mobile TOC setup into the main initialization flow in main.ts. [1] [2]

Accessibility and Style Improvements:

• Updated TOC styles to prevent unwanted transitions during collapsing (:not(.toc-collapsing)), disable tap highlight, prevent text selection on the TOC title, and use a more consistent transition duration for SVG rotation. [1] [2] [3] [4]

output.webm