Docs design updates (#41918)

* Refactor docs site styling and Shiki integration

Code Highlighting:
- Enhance Code.astro with Shiki transformers and Bootstrap theme
- Add tab support for multi-language code examples
- Add toolbar with language labels and copy button
- Support diff highlighting via @shikijs/transformers

Components:
- Update Example.astro styling and structure
- Refine DocsSidebar.astro layout
- Update Navigation, Versions, and GetStarted components
- Update ThemeToggler.astro
- Minor updates to ReferenceTable, Swatch components

Site SCSS:
- Restyle code snippets and examples (_component-examples.scss)
- Update syntax highlighting styles (_syntax.scss)
- Refine sidebar styling (_sidebar.scss)
- Update search component styles (_search.scss)
- Update navbar styles (_navbar.scss)
- Refresh callouts, clipboard, content styles

Config & Assets:
- Update astro.config.ts for Shiki
- Add sticky.js partial
- Update application.js
- Update guide screenshots (parcel, vite, webpack)

* fixes

* update images

* update permissions

* Optimised images with calibre/image-actions

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>