🔒 Fix hardcoded IndexNow API key vulnerability

[lsb11]

🎯 What: The vulnerability fixed is a hardcoded secret (IndexNow API key) in the astro.config.mjs file.
⚠️ Risk: The potential impact if left unfixed is that anyone with access to the codebase can see the hardcoded key and use it to unauthorizedly update or modify search engine indices using the IndexNow API.
🛡️ Solution: Removed the hardcoded static string and replaced it with process.env.INDEXNOW_KEY. The integration is conditionally loaded using the spread syntax ...(process.env.INDEXNOW_KEY ? [indexnow({ key: process.env.INDEXNOW_KEY })] : []) to prevent the Astro build from failing in environments where the variable is not set.

---

PR created automatically by Jules for task 9524416152967515526 started by @lsb11

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.

[cloudflare-workers-and-pages]

Deploying stackarchitect2 with    Cloudflare Pages

Latest commit:	0ae9b1e
Status:	✅  Deploy successful!
Preview URL:	https://9f711ec7.stackarchitect2.pages.dev
Branch Preview URL:	https://fix-hardcoded-indexnow-key-9.stackarchitect2.pages.dev

View logs