Fixes two bugs in the input formatter:
1. Single/double quote regex now requires word boundaries:
- Contractions like it's, don't, won't no longer trigger highlighting
- Only properly quoted text like 'special' or "hello" gets cyan
- Mixed input like "it's a 'test' case" only highlights 'test'
2. Visual line calculation fix for exact terminal width:
- When text exactly fills terminal width, cursor wraps to next line
- Added +1 adjustment to account for this edge case
- Extracted calculate_visual_lines() for testability
Added 9 new tests covering all edge cases.
Dhanji R. Prasanna
8705228fda