Restructure nav menus to match April wireframe

[rdhyee]

Context

Hana's updated Figma wireframe (2026-04-03) shows revised dropdown menu structures that differ from the current site.

Changes needed

How to Use dropdown (currently 2 items → 5)

Current: Quick Start, Data Files
Wireframe:

1. Overview
2. Deep-Dive Analysis
3. 3D Globe Visualization
4. Search Explorer
5. Technical: Narrow vs Wide

About dropdown (currently 6 items → 4)

Current: Objectives, Technical Perspective, Team, Contributors, Photo Gallery, Background & History
Wireframe:

1. Objectives
2. PIs and Contributors (merge Team + Contributors)
3. Photo Gallery
4. Background & History

Architecture & Vocabularies dropdown (4 items)

Wireframe:

1. Overview
2. Requirements
3. Schema
4. Vocabularies

Research & Resources dropdown (3 items)

Wireframe (merged from two sections per #74):

1. Publications & Conferences
2. Zenodo Community
3. Github Repositories

Hana comment

"Add subsections to menu?"

Figma reference

iSamples Wireframe 1.0

[rdhyee]

Completed in PR #89 (nav restructure matching April wireframe).