[UI] Add /experiments to navigation menu

[UI] Add /experiments to navigation menu

ID: 2077201c-c23 Priority: 89 Type: one_shot Status: open

Goal

The experiments page exists but is not linked from navigation. Add it to the top bar nav (Main group) and sidebar nav (Explore group).

Acceptance Criteria

Work Log

• 2026-04-20T22:35:00Z: Added /experiments to top bar nav (Main dropdown) and sidebar nav (Main group) in api_shared/nav.py. Commit: 9c50373a2. Note: "Explore" group does not exist in sidebar; added to "Main" group instead per intent.