Function emit_init 

pub fn emit_init(
    state: &StateBlock,
    derived: Option<&DerivedBlock>,
    ctx: &mut FuncContext,
    f: &mut Function,
) -> CodegenResult<()>

Emit the init() function (parameterless).

• Sets global gas_limit to DEFAULT_GAS_LIMIT
• Resets gas counter to 0
• Evaluates each state field’s default expression
• Builds the state record
• Evaluates derived fields