Fix prefix concatenation in timestamp post-processing for sensevoice (#2670)

slin000111

2025-09-20 88b464edb94531ba98744a5338965af539ab18ec

1
2
3
4
5
6
7
8
9
x    1
xx    2
xxx    3
xl    4
l    5
lx    6
lxx    7
lxxx    8
xc    9