feat(finetune): optional Weights & Biases logging in SFT

[Mi221e]

Summary

• Add optional W&B logging to moss_tts_local/finetuning/sft.py and moss_tts_delay/finetuning/sft.py (main process only).
• New CLI flags: --wandb-project, --wandb-run-name, --wandb-entity, --wandb-tags.
• Logs train/loss, train/lr, throughput, and train/epoch on the same cadence as --logging-steps.
• Add wandb>=0.16.0 to [project.optional-dependencies] (finetune, finetune-deepspeed).

Usage

accelerate launch ... moss_tts_local/finetuning/sft.py \
  --train-jsonl data.jsonl \
  --wandb-project my-project