Make Risk Model Parameters Configurable

[YanCotta]

Description: The risk_weights and risk_thresholds in RiskAssessmentService are hardcoded. This makes it difficult to adjust the risk model without changing the code. These parameters should be loaded from the application settings.

Tasks:

Move the risk_weights and risk_thresholds to the settings.py file.

Load these parameters from environment variables or a configuration file.

Update the RiskAssessmentService to use the values from the settings.

Relevant Files:

src/climate_risk/application/services/risk_service.py

src/climate_risk/config/settings.py