feat(voyageai): rebrand to 'VoyageAI by MongoDB' and refresh model list

[fzowl]

What & why

VoyageAI is now part of MongoDB. This updates the VoyageAI-related parts of the client accordingly and refreshes the model catalog to VoyageAI's current offerings (verified against docs.voyageai.com, Sept 2026).

(1) Open-PR review

Reviewed all open PRs on the fork (none) and upstream weaviate/java-client (weaviate#598, weaviate#608, weaviate#609, weaviate#610, weaviate#612, weaviate#613, weaviate#616 — all by @dudanogueira). No fzowl/fzoll fork-PRs exist, so nothing to carry over.

(2) Rebrand — 'VoyageAI by MongoDB'

Updated user-visible prose only:

• Reranker.voyageai() / voyageai(fn) Javadoc.
• Added class-level Javadoc to Text2VecVoyageAiVectorizer, Multi2VecVoyageAiVectorizer, VoyageAiReranker naming the provider.

Left untouched (not user-visible text, changing them breaks the API/wire protocol): class/method/enum identifiers and module strings such as text2vec-voyageai, multi2vec-voyageai, reranker-voyageai. There is no website/UI/README copy in this repo mentioning VoyageAI.

(3) Refreshed model list

Added current models as constants, kept legacy ones for backward compatibility (removing public constants would be a breaking change):

• text2vec: voyage-4-large, voyage-4, voyage-4-lite, voyage-code-4, voyage-finance-2, voyage-law-2, voyage-context-4
• multi2vec: voyage-multimodal-3.5 (legacy voyage-multimodal-3)
• reranker: rerank-3, rerank-3-lite, rerank-2.5, rerank-2.5-lite

(4) Contextual models — scope note

The contextualized_embed runtime API (inputs: list[str], enable_auto_chunking=true, chunk_size=32000) is part of the VoyageAI Python SDK, not this Java client. In Weaviate, embeddings run server-side in the text2vec-voyageai module; the client only declares the module config (model, baseURL, truncate, dimensions). There is no client-side embed call and the module config has no enable_auto_chunking/chunk_size fields, so those parameters are not applicable here. The contextual model itself (voyage-context-4) is now exposed as a constant. Fabricating unsupported wire fields was deliberately avoided.

Validation

• mvn compile — clean.
• mvn -Dtest=JSONTest test — 222 passed, 0 failures (serialization of these vectorizers/rerankers).
• git diff --stat touches only the 4 VoyageAI files.

[fzoll]

Visszavonva (Fődi kérése): a kampányt egyenkénti, ellenőrzött feldolgozásra állítjuk. A branch megmarad.

[fzowl]

Visszavonva (tulaj kérése): a kampány egyenkénti, ellenőrzött feldolgozásra állt át. A branch megmarad.