model_hf: aubmindlab/bert-base-arabertv02-twitter
train_csv: data/track1/train.csv
dev_csv: data/track1/dev.csv
out_dir: outputs/t1_arabert
seed: 42
max_len: 128
batch_size: 16
eval_batch_size: 64
lr: 2.0e-5
weight_decay: 0.01
epochs: 12
patience: 3
loss: ce            # ce | weighted | focal | focal_weighted
focal_gamma: 2.0
prep_mode: preserve  # preserve | baseline  (ablation)
use_description: false
none_bias: 0.0       # tune <0 on dev to suppress None for Favg2