fix(asm): treat the arm64 $-8 frame as frameless and encode the RET forms

Assisted-by: GLM 5.3 Flash

asm/arm64_assemble.go

@@ -396,7 +396,7 @@ func encodeARM64Instr(instr *ast.Instr, pc int, offsets map[string]int, fi arm64
 	// Pseudo-instructions and special cases first.
 	switch mnem {
 	case "RET":
-		return arm64Return(fi), nil
+		return arm64RetInstr(fi, ops, relocs), nil
 	case "NOP", "NOOP":
 		return a64wordLE(a64NOP), nil
 	case "UNDEF":