Draft: Add a "Join the Lab / For Students" page

[kcarnold]

Draft proposal for the summer student backlog — open for the director's review before anyone picks it up. Suggested label: content, good first issue.

Why

The site has no page describing what it's like to be in the lab or how to get involved. The About page's "Contact" section is the closest thing, and it only points people to the publications/projects pages. For a lab that wants to recruit and grow student researchers, this is the biggest content gap.

What to add

A new page (e.g. /join or /students) that covers:

• What student researchers actually do in the lab (research, design, development) and how that connects to the lab's vision of AI that helps people think better, not faster.
• What students gain (skills, publications, conference experience — we have In2Writing/NAACL and HAI-GEN examples to point to).
• Who it's for and how to apply / express interest (link to Ken at https://kenarnold.org).
• A pointer to the writing-tools repo and this repo as places students contribute.

Notes

• Add the page to the header nav (src/components/lab/LabHeader.tsx) and footer (src/components/lab/LabFooter.tsx).
• This is a great writing-heavy first contribution — a current student could draft it from their own experience.

Done when

• Page builds (npm run build) and is linked from the nav.
• Content is reviewed/approved by the lab director.