Increase max loan amount to $10M in early mortgage payoff calculator

The previous limit of $1M was causing validation errors for users with
higher-value mortgages. Increased to $10M to accommodate modern housing
market prices.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Shpigford

app/presenters/tool/presenter/early_mortgage_payoff_calculator.rb

@@ -1,5 +1,5 @@
 class Tool::Presenter::EarlyMortgagePayoffCalculator < Tool::Presenter
-  attribute :loan_amount, :tool_float, default: 500_000, min: 0.0, max: 1_000_000.0
+  attribute :loan_amount, :tool_float, default: 500_000, min: 0.0, max: 10_000_000.0
   attribute :extra_payment, :tool_float, default: 500.0
 
   attribute :interest_rate, :tool_percentage, default: 6.5