When users type prompts in interactive mode, the input is now
reformatted in place with enhanced highlighting:
- ALL CAPS words (2+ chars) become bold green (e.g., FIX, BUG, HTTP2)
- Quoted text ("..." or ...) becomes cyan
- Standard markdown formatting is also supported
New module: input_formatter.rs with 10 unit tests
Integrated into interactive.rs for both single-line and multiline input
