Improve keyboard navigation for form controls

[thomasbecker]

Problem

Forms in the app are difficult or impossible to navigate using keyboard only. This is an accessibility barrier for users who rely on keyboard navigation.

Specific Issues

• Select/dropdown components (like the brand selector on the "Add Gear Item" form) cannot be operated with keyboard alone
• Users must use a mouse to select options from dropdown menus
• This blocks keyboard-only users from completing core workflows

Expected Behavior

• All form controls should be fully operable via keyboard
• Select boxes should support:
  • Tab to focus the control
  • Enter or Space to open the dropdown
  • Arrow keys to navigate options
  • Enter to select an option
  • Escape to close without selecting
• Focus should be clearly visible on all interactive elements

Impact

This affects users who:

• Have motor impairments that make mouse use difficult
• Prefer keyboard for efficiency
• Use screen readers or other assistive technology

Technical Notes

This likely requires reviewing the shadcn-svelte Select component usage to ensure proper keyboard event handling and ARIA attributes are in place.