FEAT: Add unread count to folder list

[andrinoff]

Is your feature request related to a problem? Folder list shows folder names only. Cannot see which folders have unread mail without opening each one.

Describe the solution you would like: Show unread count next to folder name:

• Inbox (23)
• Sent
• Drafts (2)

Update count when emails marked read/unread.

Describe alternatives you have considered: No count (current). Count improves navigation efficiency.

Additional context:

• File: tui/folders.go or folder display code
• Track unread count per folder
• Update on email status change
• Complexity: Easy-Medium - state tracking

[floatpanebot]

This has had no activity for 30 days. It will be closed in 14 days unless updated. Comment or remove the stale label to keep it open.

[mavonx]

/assign