feat: support Jina AI v5 Matryoshka embedding models (nano + small)

[metaphorics]

Goal

Add support for Jina AI's v5 Matryoshka text-embedding models (jina-embeddings-v5-text-{nano,small}-retrieval) as selectable backends in ICM, with full plumbing for Matryoshka truncation, asymmetric retrieval, and auto re-embed when the active model's dimension changes.

Jina v5 lifts MTEB English v2 to ~71 (small 1024d, nano 768d) and ships ONNX exports with Matryoshka representation learning (truncate dims down to 32) and asymmetric retrieval.query: / retrieval.passage: instruction prefixes.

License caveat

Jina v5 weights are CC BY-NC 4.0 (non-commercial). Surfaced clearly in README, config/default.toml, and icm config show. Default backend remains fastembed (Apache-2.0).

Slice plan (all DONE locally — see PR)

• S-store — refactor schema migration to return MigrationStatus (decouples store from embedder)
• S-1 — Embedder trait extension (embed_query, embed_document, model_name, license) + JinaV5NanoEmbedder via ort + tokenizers + hf-hub
• S-2 — JinaV5SmallEmbedder (Qwen3-based, dim 1024)
• S-3 — auto re-embed on dim change with --no-auto-reembed opt-out flag
• S-4 — asymmetric retrieval prefixes (retrieval.query: / retrieval.passage: ) via internal TextEncoder DI for testability
• S-5 — docs/UX/license disclosure (README, config/default.toml, icm config show, recall header, CHANGELOG)

Verification

• cargo test --features "embeddings jina-v5" — 310 passed (8 suites)
• cargo clippy --features "embeddings jina-v5" -- -D warnings — clean
• All Codex spec + quality reviews PASS per slice

Upstream Track 2

A registration-only patch for Anush008/fastembed-rs adding EmbeddingModel::JinaEmbeddingsV5TextNano is being submitted in parallel (separate PR upstream). The v5-small Qwen3-decoder path is blocked on upstream architecture (closed PR #236 attempted it); ICM ships its own ort integration in icm-core for the local consumer use case.

References

• Jina v5 collection: https://huggingface.co/collections/jinaai/jina-embeddings-v5-text
• Plan file: .claude/plans/support-latest-jina-ai-s-fuzzy-crystal.md (local)
• Slice doc: docs/issues/jina-v5-slices.md (in tree)

[pszymkowiak]

wshm · Automated triage by AI

🔍 Automated Triage

✨ Category	feature
🟡 Priority	medium
🎯 Confidence	95%

Summary

Well-scoped feature request to add Jina AI v5 Matryoshka embedding model support; PR already submitted with all slices completed and tests passing.

📁 Relevant files

• config/default.toml
• docs/issues/jina-v5-slices.md

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Triaged automatically by wshm · This is an automated analysis, not a human review.