Update Gemini Embedding model to v2 (GA)

[g-despot]

Summary

Google's Gemini Embedding 2 moved to General Availability on 2026-04-23. This PR updates the docs to reflect the new stable model ID and expanded modality support.

• Renamed gemini-embedding-2-preview → gemini-embedding-2 across docs, code examples, and includes (the preview string will be deprecated in a few weeks)
• Added audio as a supported modality for gemini-embedding-2 in embeddings-multimodal.md (Gemini API only, audio files up to 180 seconds)
• Marked the model as "GA as of 2026-04-23" in the available-models lists for both embeddings.md and embeddings-multimodal.md

Files changed

• docs/weaviate/model-providers/google/embeddings.md — available-models lists for Gemini API and Vertex AI
• docs/weaviate/model-providers/google/embeddings-multimodal.md — callout, vectorizer params reference, available-models list
• docs/weaviate/model-providers/_includes/provider.vectorizer.py / .ts — shared code examples
• docs/weaviate/search/near-media.md — prose references
• _includes/code/howto/search.near-media.py — tested code snippet

Test plan

• CI passes on the Python test suite (_includes/code/howto/search.near-media.py runs against the renamed model)
• Docusaurus build passes
• Preview build: spot-check the "Available models" sections on both Google embeddings pages
• Preview build: verify the near-media page renders correctly with the updated model references

Follow-ups (not in this PR)

• Google SDK will add an audio_track_extraction parameter in next week's release for audio tracks in video files — revisit docs when that ships
• There is a behavioral change in embedding aggregation in the latest Google SDK vs. gemini-embedding-001 / gemini-embedding-2-preview when submitting multiple files in a single embed call; worth verifying downstream client behavior separately

🤖 Generated with Claude Code

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