Improve logging consistency in install scripts

## Problem
Current install scripts use echo for all output without distinguishing between different types of messages (info, warning, error).

## Solution
Implement separate logging functions to improve clarity:
- `log_info()` - for informational messages
- `log_warning()` - for warning messages
- `log_error()` - for error messages

## Scope
- `utils/install-claude-code.sh`
- Other install scripts in `utils/` directory

## Benefits
- Better visual distinction between message types
- Consistent logging format across all scripts
- Easier debugging and troubleshooting

Identified in PR #502 review by Amazon Q Developer.

Start by reading utils/install-claude-code.sh and then inspect the other install scripts in utils/ for their current echo usage. Identify the message types each script emits and define a consistent approach for info, warning, and error output. Done means the scoped scripts use the separate logging functions with a consistent format.

Written by the indexing model from the issue text.