KOS_OP_TAIL_CALL_VAR

• Style: EXTRA. Schema: VAR (name cpool idx), COUNT (npos), NOARG, NOARG.

• Stack: Same layout as CALL_VAR: [..., pos_0, ..., pos_{N-1}]; the callable is loaded from the frame namespace by name, not on the stack. Tail semantics as KOS_OP_TAIL_CALL_ATTR: the caller’s frame is reused rather than a new frame pushed.

• Compiler form: Promotion relabel of a tail-position CALL_VAR; convert_fast lowers it to TAIL_CALL_FAST when the name has a fast slot.