PP-OCRv6 recognition uses CTC and NRTR heads to curb hallucination

PP-OCRv6's recognition module uses a CTC plus NRTR dual-head design so text is decoded from visual features rather than language priors, reducing hallucination.

In hallucination tests, PP-OCRv6_medium reaches 93.2%, versus 85.0% for the best VLM, and recognition accuracy across 15 scenarios is 83.2%, above PP-OCRv5_server's 78.1%.

NRTR is used only during training, adding language regularization at no inference cost, and it contributes +1.16% accuracy.