Update people: Mark 5 members as alumni and add 4 new members

[Copilot]

This PR updates the people section of the website to reflect current lab membership changes.

Alumni Updates

The following 5 members have been marked as alumni by setting alumni: true in their profile files:

• Brad Karat - PhD student, Neuroscience
• Alaa Taha - PhD Student, Biomedical Engineering (co-supervised by Dr. Jonathan Lau)
• Farah Mushtaha - Master's student, Medical Biophysics (co-supervised by Dr. Corey Baron)
• Mohamed Yousif - Undergraduate student, Medical Biophysics
• Mackenzie Snyder - Research Software Developer Co-op Student, Medical Biophysics (co-supervised by Dr. Jonathan Lau)

New Members

Four new lab members have been added with profile files following the existing template structure:

• Dilyar Deniz - Master's Student, Medical Biophysics (co-supervised by Dr. Jonathan Lau)
• Luke Smolders - Master's Student, Medical Biophysics (co-supervised by Dr. Taylor Schmitz)
• Arshya Pooladi-Darvish - Master's Student, Medical Biophysics
• Victor Lau - PhD Student, Medical Biophysics (co-supervised by Dr. Shawn Whitehead)

Technical Details

• Files follow the naming convention using month codes: 03 for PhD students, 04 for Master's students
• All YAML front matter has been validated
• Changes are minimal and surgical - only the alumni field was modified for existing members
• New member files use the standard template with placeholder image paths and empty social fields that can be filled in later

Fixes issue requesting people updates.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>update people</issue_title>
<issue_description>- a bunch of people are now alumni

• brad
• alaa
• farah
• mohamed
• mackenzie

also new people:

• Dilyar Deniz - Masters with Jon Lau

• Luke Smolders - Masters with Taylor Schmitz

• Arshya Pooladi-Darvish - Masters

• Victor Lau - PhD with Shawn Whitehead

• update statuses and add new people</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #90

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