Rebuild the bge-m3 semantic index via canonical EMBEDDING-PIPELINE — one keystone build feeds reader related-articles (src/data/related) + RAG vectors (public/api/rag). Sovereignty-preserving: embeddings computed in-house (mac-m4max local primary, GPU fleet fallback), never outsourced. TRIGGER when: user says "重建語意索引", "跑 embeddings", "rebuild embeddings", "embedding routine", or routine `twmd-embeddings-nightly` fires.