feat: add pivot component and selector with directive support

[IEvangelist]

• Implemented Pivot component to serve as a container for pivot blocks.
• Created PivotSelector component to manage pivot options and their display.
• Added styling for the pivot components to enhance UI/UX.
• Developed pivot-directive to transform pivot directives in markdown into corresponding HTML elements.
• Integrated local storage and URL query parameters for persistent state management of selected pivot options.

C#

Python

[Copilot]

Pull Request Overview

This PR adds a language pivot/selector feature to the documentation, enabling users to switch between C#, Python, and JavaScript examples on the "first app" guide. The implementation includes interactive UI components for language selection with state persistence.

• Adds pivot selector UI components with local storage and URL query parameter persistence
• Updates the getting started guide with language-specific content for C#, Python, and JavaScript
• Configures HSTS security options in the static host
• Adjusts file tree font sizing for better visual consistency

Reviewed Changes

Copilot reviewed 8 out of 14 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/statichost/StaticHost/Program.cs	Adds HSTS configuration with preload and subdomain options
src/frontend/src/styles/site.css	Sets font size for file tree components
src/frontend/src/directives/pivot-directive.mjs	Implements remark directive processor for pivot blocks
src/frontend/src/content/docs/get-started/first-app.mdx	Adds multi-language pivot selector and language-specific content
src/frontend/src/components/PivotSelector.astro	Creates interactive language selector component
src/frontend/src/components/Pivot.astro	Creates pivot content block wrapper component
src/frontend/package.json	Adds remark-directive dependency
src/frontend/package-lock.json	Updates dependency lock with remark-directive v4.0.0
src/frontend/astro.config.mjs	Configures MDX and remark plugins for pivot directives

Files not reviewed (1)

• src/frontend/package-lock.json: Language not supported