refactor: Implement proper logging strategy

[greynewell]

Problem

The codebase has many `console.error('[DEBUG] ...')` statements for informational logging. Issues:

1. Debug logs go to stderr - Informational messages should use stdout
2. No log levels - Can't distinguish info/warn/error/debug
3. Always enabled - No way to disable debug logging in production
4. Inconsistent format - Some use [DEBUG], [ERROR], [WARN], some don't

Proposed Solution

Either:

Option 1: Simple - Environment Variable

const DEBUG = process.env.DEBUG === 'true';

function debug(msg: string, ...args: any[]) {
  if (DEBUG) console.error('[DEBUG]', msg, ...args);
}

function info(msg: string, ...args: any[]) {
  console.log('[INFO]', msg, ...args);
}

Option 2: Structured Logger
Use a library like pino or winston for proper log levels, structured output, and configuration.

Benefits

• Cleaner production logs
• Configurable verbosity
• Better debugging experience
• Consistent log format