Peephole optimizations in _assign() eliminate __CT_RET and __ct_tmp
round-trips by retargeting assignments directly to the target variable.
Boolean condition peephole in _condition_bash() extracts test expressions
directly instead of going through __CT_RET. Static dispatch for this
method calls uses class_name to emit direct function calls instead of
dynamic __ct_call_method. Class metadata (_fields/_types) only emitted
when reflect/json categories are used. Stdlib methods (math, args, core)
use direct __CT_RET= instead of echo to avoid subshell forks.