feat(cli): add click-to-position cursor and selection-aware delete

- Click anywhere in input box to move cursor to that position - Handles
multiline input with word-wrap, tabs, and scroll position -
Delete/Backspace now deletes selected text instead of single char -
Typing with selection replaces selected text - Selection highlight
clears properly after deletion - Refactored keyboard handler into
smaller focused functions - Added handleSelectionDeletion helper to
reduce code duplication - Use theme.info color instead of hardcoded
highlight color - Removed unused measuredCols state and deprecated width
prop

Author: brandonkachen