Add navigation arrows to Photo Gallery

[rdhyee]

Wireframe spec

Hana's wireframe (frame [151:1186]) shows the Photo Gallery with left/right navigation arrows for browsing photos, suggesting a carousel or slideshow interaction.

Current state

The About page Photo Gallery is a static 3-column grid of 6 images. No navigation or carousel behavior.

Options

1. CSS/JS carousel — lightweight carousel with prev/next arrows (could use Quarto's built-in lightbox or a small JS library)
2. Lightbox only — clicking a photo opens it larger with prev/next navigation (Quarto has lightbox: true support)
3. Keep grid, add lightbox — simplest, preserves current layout, adds click-to-enlarge with navigation

Option 3 is probably the right balance: grid for overview, lightbox for browsing.

Analysis from Figma API scan of wireframe frames [151:1186] and [151:1192].