Fix: Wrap LoRA loading and offloading in defer_i2v_loading check

When defer_i2v_loading=True (I2V mode without provided image), the code
sets pipe=None but then tried to call pipe.load_lora_weights() and
pipe.enable_model_cpu_offload() on None, causing AttributeError.

This fix wraps the LoRA loading and offloading configuration blocks
inside an 'if not defer_i2v_loading:' condition so they are skipped
when the I2V model loading is deferred until after image generation.