Inconsistent API error handling

[ECWireless]

Problem: API routes have varying error handling patterns

Examples:

// Some routes
console.error(err);
return res.status(500).end();

// Other routes
console.log(err);
return res.status(500).json(null);

// Better approach
console.error(err);
return res.status(500).json({ 
  error: 'Internal server error',
  code: 'INTERNAL_ERROR' 
});

Recommendation: Standardize error responses
Impact: Better client-side error handling

[ECWireless]

Closed by #483