feat(htmlmark): add HTML ↔ Markdown conversion component

[samsameer2804-cloud]

Closes #13

Summary

This PR adds a new component htmlmark for transforming HTML into clean Markdown, following the component structure used in this repository.

Features

• Extracts main content from HTML using readability (with fallback to raw HTML)
• Converts HTML → Markdown using html2md
• Optional Markdown → HTML rendering using pulldown-cmark
• Pure implementation (no network calls)

Interface

• extract(input: string) -> result<string, string>
• render(md: string) -> result<string, string>

Structure

• components/components/htmlmark/
  • wit/world.wit – interface definition
  • src/lib.rs – implementation using wit-bindgen
  • Cargo.toml – component configuration

This follows the same structure and conventions as existing components like wordmark and tablemark.

Notes

• Includes fallback behavior if content extraction fails
• Keeps implementation minimal and focused on the core requirement

[samsameer2804-cloud]

@yoshuawuyts Fixed the folder structure (removed duplicate files at components/src/ and components/wit/), added semicolons to world.wit, and corrected import ordering in lib.rs. CI should pass now!