Replace AI Studio gemini-embedding-001 with Vertex AI text-multilingual-embedding-002
via google-genai SDK (vertexai=True). Vertex AI uses ADC (already configured) and
has significantly higher per-project quotas than AI Studio per-user limits.
Same 768-dim output; multilingual model better suited for 50+ language glossaries.
Add gcp_location config field (default us-central1).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>