Fix infinite loop in wordLeft when at buffer start

[hamid-husain]

There is a critical hang in the textarea component. Calling wordLeft() (triggered by Alt+b or Alt+Left) while the cursor was at the beginning of an empty or space-filled buffer would result in an infinite loop.

The Issue
In the current implementation of wordLeft():

• The first for loop calls m.characterLeft(true).
• If the cursor is at (0,0), characterLeft does not change the cursor position.
• The loop condition !unicode.IsSpace(...) is never met because the cursor never moves to a new character.
• The loop runs indefinitely, pinning the CPU and freezing the TUI.