Add input formatting for interactive CLI

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

crates/g3-cli/src/lib.rs

@@ -23,6 +23,7 @@ mod g3_status;
 mod template;
 mod completion;
 mod project;
+mod input_formatter;
 
 use anyhow::Result;
 use std::path::PathBuf;