[patrickdappollonio]

This PR updates the website's packages to remove all open security alerts. One alert is critical: in Astro, the tool that builds the site, an attacker can run code through a bad AVIF image. After this change, npm audit finds no vulnerabilities.

The changed packages are:

• Astro goes from 7.1.3 to 7.3.5. Astro 7.3 needs a newer Markdown plugin, so @astrojs/markdown-remark goes from 7.2 to 7.3.1.
• sharp (image processing) goes from 0.35.3 to 0.35.5.
• Vitest (the test tool) goes from 4.1.10 to 4.1.11.
• js-yaml, svgo, nanoid and devalue get security fixes. These packages come in through other packages, so only the lock file changes for them.

This PR replaces Dependabot PRs #275, #276, #277, #278, #279 and #280. It also fixes the nanoid alert, which has no Dependabot PR. The Rust app does not change.