Create a user settings page with tabbed navigation:

LAYOUT:
- Sidebar navigation (tabs) on left
- Content area on right
- Tabs: Profile, Account, Notifications, Security, Billing

PROFILE TAB:
- Avatar upload (with preview)
- Full name
- Email (read-only or editable)
- Bio/Description (textarea)
- Phone number
- Location
- Website
- Social media links
- "Save Changes" button

ACCOUNT TAB:
- Username
- Email preferences
- Language selector
- Timezone selector
- Date format preference
- "Delete Account" button (danger zone at bottom)

NOTIFICATIONS TAB:
- Email notifications (toggle switches):
  * Product updates
  * Newsletter
  * Account activity
  * Marketing emails
- Push notifications (if applicable)
- Notification frequency (dropdown)
- "Save Preferences" button

SECURITY TAB:
- Change password section:
  * Current password
  * New password
  * Confirm new password
  * Password strength indicator
- Two-factor authentication:
  * Enable/Disable toggle
  * Setup instructions
- Active sessions:
  * List of devices/locations
  * "Sign out" button for each
- "Sign out all devices" button

BILLING TAB:
- Current plan display
- "Upgrade Plan" button
- Payment method:
  * Card ending in ****
  * "Update Payment Method" button
- Billing history table:
  * Date, Description, Amount, Status
  * "Download Invoice" links
- Billing address

STYLING:
- Clean, organized layout
- Clear section separators
- Consistent form styling
- Danger zone styling for destructive actions (red)
- Success messages after saves
- Mobile responsive (tabs become dropdown on mobile)