fix: duplicated operator handling

[Generated by Duo]

Relates to issue #75 (closed)

Changes

• Extended duplicate operator validation from only in operators to all operator types (=, >, >=, <, <=, in)
• Updated analyze_expressions() to track all operators with a HashMap<Operator, IndexSet<Field>> instead of just tracking in operators
• Added field type checking to implement special handling for list-like fields (only in operator duplicates are checked for list fields)
• Modified error handling to display dynamic operator descriptions instead of hardcoded "in" message
• Updated DuplicateOperatorForField error variant to include both field and operator parameters
• Added 10 comprehensive test cases covering all operator types and edge cases
• Ensured backward compatibility while matching TypeScript implementation behavior from MR !261 (merged)