Function load_effective_rules 

pub fn load_effective_rules(
    config: &Config,
    sources: &[ResolvedSource],
) -> Result<Vec<Rule>, RuleError>

Load all effective rules based on config: builtin, custom rules from configured directories, and rules from resolved external sources, all filtered by is_rule_active (rulesets, enabled: false, and the enable/disable lists). An external rule reusing a builtin id is rejected before any filtering.