Unit Tests for Rule Parser and Evaluation

[slint]

The rule parsing and evaluation functionality needs dedicated tests to ensure that rules are correctly parsed from their JSON configuration and evaluated against records.

Test Cases to Implement

1. ExpressionParser

   • Test parsing each type of expression (field, comparison, logical, list)
   • Test error handling for invalid expression configurations
   • Test parsing nested expressions

2. RuleParser

   • Test parsing complete rules with conditions and checks
   • Test parsing rules without conditions
   • Test error handling for invalid rule configurations

3. Rule Evaluation

   • Test rule evaluation when condition is met
   • Test rule evaluation when condition is not met
   • Test rule evaluation with multiple checks
   • Test rule evaluation results format

[slint]

Done via #1