fix(tests): add CI failure tolerance and fix 4 embedding tests (Section 5/5)

[yehudit1987]

Disable Gemma embedding model in CI tests since it's a gated model
requiring HF_TOKEN. Tests now use Qwen3-Embedding-0.6B exclusively.

This approach was discussed and approved by maintainers who decided
to focus on Qwen3 (non-gated) for CI tests.
See: https://github.com/vllm-project/semantic-router/issues/573#issuecomment-3607352121

Changes in candle-binding/semantic-router_test.go:

• Set GemmaEmbeddingModelPath to empty string (disable Gemma)
• Update dimension expectations from 768/1024 to 1024 (Qwen3)
• Skip InitGemmaOnly test with clear explanation
• Remove conditional skip logic that was masking test failures
• Update comments to clarify Qwen3-only and Matryoshka usage

Changes in tools/make/models.mk:

• Add Qwen3-Embedding-0.6B to minimal download target for CI
• Remove Gemma from lora download target
• Improve download tracking with .downloaded marker files

Qwen3-Embedding-0.6B is fully open (no gating) and supports
Matryoshka dimension truncation (768/512/256/128) from its
native 1024 dimensions.

Resolves #573 (Section 5: Embedding Model Tests)

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[github-actions]

👥 vLLM Semantic Team Notification

The following members have been identified for the changed files in this PR and have been automatically assigned:

📁 candle-binding

Owners: @rootfs
Files changed:

• candle-binding/semantic-router_test.go
• candle-binding/src/classifiers/unified.rs
• candle-binding/src/ffi/embedding.rs

📁 tools

Owners: @yuluo-yx, @rootfs, @Xunzhuo
Files changed:

• tools/make/models.mk
• tools/make/rust.mk

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🎉 Thanks for your contributions!

This comment was automatically generated based on the OWNER files in the repository.