🔒 Fix path traversal and injection in service logs endpoint

[scobru]

🎯 What: Fixed a path traversal and injection vulnerability in the /services/:name/logs endpoint in relay/src/routes/system.ts.
⚠️ Risk: The endpoint was vulnerable to bypasses because the \s in its validation regex matched newlines and other control characters, and the redundant .replace(/%20/g, " ") decoding could allow attackers to smuggle bad paths using double encoding or other unexpected characters. This could allow attackers to read arbitrary files on the host filesystem.
🛡️ Solution: Updated the regex /^[a-zA-Z0-9\s\-_]+$/ to /^[a-zA-Z0-9 \-_]+$/ to restrict whitespace strictly to spaces, and removed the redundant %20 replacement as Express handles URL decoding by default.

---

PR created automatically by Jules for task 3483134159954623410 started by @scobru

[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.