Fix remaining tail burst in samples (improved burst detection)

Regenerate all samples with tail cleanup (no clicks)

Fix end-of-audio artifacts in samples (trim trailing burst, add fade-out)

Update ngoc_huyen sample

Update gia_bao, huu_dat, phuong_linh, thanh_phong samples

Regenerate all voice samples at speed 1.05

Regenerate phuong_linh sample with new sentence

Regenerate ngoc_huyen sample

Add synthesized voice samples