[Enhancement]: Make toast duration configurable

[rubentalstra]

Description

Toast notification duration is hardcoded to 5 seconds. Users should be able to configure this based on their reading speed and preferences.

Problem

• Hardcoded 5-second duration may be too short for detailed error messages
• May be too long for simple confirmations
• Accessibility concern for users with different reading speeds

Location

Toast component in tss-gui/src/component/feedback/

Suggested Fix

1. Add duration field to Toast struct
2. Add setting to Settings for default toast duration
3. Allow per-toast duration override
4. Consider different defaults for different toast types:
   • Success: 3s
   • Info: 5s
   • Warning: 7s
   • Error: 10s (or until dismissed)

Iced 0.14.0 Best Practice

User-configurable UI timing improves accessibility and user experience.

Priority

Low - UX improvement.