Estimate confidence warning when using default pricing instead of catalog data

When an estimate uses Home Depot or other default pricing instead of the customer's own catalog data, show a visible confidence warning before sending to the client.

This would prevent situations where estimates are significantly off because default pricing was used instead of actual local rates. Real example: A customer's kitchen remodel estimate came back at $35k using defaults, but the real cost was $50-55k — leading to a bad client review.

A simple warning like 'This estimate uses default pricing for 12 line items — review before sending' would have prevented this.