Regenerate pnpm-lock.yaml for main branch dependencies

Fix lockfile mismatch by regenerating for main branch's package.json (vanilla JS/Vite setup). Removes Astro dependencies that were incorrectly included from astro branch.

- Removed: @astrojs/mdx, astro, and 295 related packages
- Matches: katex and marked dependencies only

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: stared