feat: implement UI improvements and accessibility enhancements

[AlexVOiceover]

Visual Improvements

• Change completed indicator color: Update completed status indicators from gray to teal for better visual hierarchy
• Update terminology: Replace all instances of "Archived" with "Inactive" throughout the application for clearer user understanding

Font Size & Accessibility

• Increase base font size: Improve readability by increasing default font sizes across the app
• Add font size control: Implement dynamic font sizing mechanism
  • Add font size icon to header area
  • Allow users to cycle through font sizes (small/medium/large) on click
  • Persist user preference (localStorage or user settings)
  • Apply size changes globally across the application

Acceptance Criteria

• All completed indicators use teal color instead of gray
• No references to "Archived" remain - all replaced with "Inactive"
• Font sizes are noticeably larger and more readable
• Font size control is accessible and intuitive in header
• Font size preference persists across sessions

Technical Notes

• Consider using CSS custom properties (variables) for dynamic font sizing
• Ensure font size changes respect existing responsive breakpoints
• Update any database queries/filters that reference "archived" status
• Test email preview layout with various email address lengths