Function register_canonical 

pub fn register_canonical(type_name: &str, planning_id: &Value, entity: Value)

Registers a canonical entity in the thread-local registry.

Call this during Phase 1 (value range provider deserialization) to register the canonical version of each entity.

Arguments

• type_name - The entity type name (e.g., “Visit”, “Employee”)
• planning_id - The entity’s planning ID value
• entity - The canonical entity Value to store