docs: add Hanzilla Jobs to student resources

[hanzili]

Summary

• Adds Hanzilla Jobs as a Canada-specific student jobs resource in the Jobs, Internships and PEY Co-op section.
• Links directly to the internships/co-ops landing page so students can find current Canadian internships, co-ops, new grad, junior, and entry-level roles.
• Keeps the mention concise and broad across tech, engineering, business, finance, sciences, arts, and other fields.

Why

UofT students reading this guide may benefit from a current, Canada-focused student/recent-grad jobs board alongside the existing CSSU job resources link.

Test plan

• Reviewed markdown diff.
• Ran git diff --check.