Add dark mode support to user dashboard

[ascherj]

Users have been requesting dark mode support for the dashboard. This would improve usability during evening hours and reduce eye strain.

Proposed Implementation

• Add theme toggle in user settings
• Persist theme preference in localStorage or user profile
• Support system preference detection (prefers-color-scheme)

Design Resources

Figma mockups available: [link to designs]

Acceptance Criteria

• Dark mode toggle in settings menu
• All dashboard pages support dark theme
• Theme preference persists across sessions
• Smooth transition between themes

Nice to have:

• Keyboard shortcut to toggle theme (Cmd/Ctrl + Shift + D)
• Automatic theme switching based on time of day

Estimated effort: 3-5 days