Add sequence_dim param to apply_rotary_emb (supports [B,S,H,D] FLUX layout alongside existing [B,H,S,D] default). Add freqs_dtype and repeat_interleave_real aliases to get_1d_rotary_pos_embed for Diffusers-compatible call sites. Remove diffusers.models.embeddings import from fastvideo/models/dits/flux.py.