Update self-references after rename to Sienna-v2-1B (backbone now Cijov-lang-v1-1B)

Update references to renamed backbone (cijov-lang-1B-v1), drop .0 from self-naming, add Sienna logo

Fix: re-export with corrected key-remapping (previous upload silently failed to load most LoRA weights due to a naming mismatch after the backbone rename -- see cijov-lang-1B-1V history)

Sienna-v2.0: initial release (LoRA merged into standalone checkpoint, CijovLang architecture)

initial commit