Fixes three bugs in the input formatter introduced in 4e16942:
1. Bug 2 & 3 (missing newline, line duplication):
- Changed print! to println! to add trailing newline
- Calculate visual lines based on terminal width instead of
logical line count, fixing duplication for wrapped lines
2. Bug 1 (^M on non-interactive prompts):
- Added TTY check to skip formatting when stdout is not a terminal
- Prevents terminal state corruption for stdin prompts
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