feat(sdk): update SDK for coordinode-server v0.4.1 API

[polaz]

Problem

coordinode-server v0.4.1 released with breaking proto change: TextService.HybridTextVectorSearch RPC removed. Python SDK still ships this endpoint, which will fail against v0.4.x servers.

Solution

Full SDK update aligned with v0.4.1:

1. Bump submodules: coordinode-rs → v0.4.1, proto → eb472a4
2. Regenerate proto stubs
3. Remove CoordinodeClient.hybrid_text_vector_search() (async + sync) — breaking removal with clear error pointing to Cypher replacement (rrf_score() / hybrid_score())
4. Audit langchain + llama-index adapters for removed RPC usage
5. Update demo notebooks (langchain / llama-index / colab) if affected
6. Run full test suite (unit + integration) against v0.4.1 server

Acceptance

• All proto stubs regenerated from eb472a4
• No references to HybridTextVectorSearch / hybrid_text_vector_search remain
• Unit + integration tests green against v0.4.1 Docker image
• All three demo notebooks run end-to-end

Estimate

~4h (bump + regen 30m, remove+audit 1h, notebooks 1h, testing 1.5h)

[coderabbitai]

🔗 Related PRs

#2 - fix: SDK API correctness — constructor, cypher result, VectorResult fields [merged]
#15 - fix: CoordiNode Cypher compatibility — add_graph_documents, type/label, MATCH+CREATE [merged]
#18 - build(deps): bump minimum coordinode requirement to >=0.4.0 [merged]
#40 - ci(release): fix embedded wheel builds for Windows, macOS, and Linux aarch64 [merged]
#44 - fix(langchain): catch gRPC errors in keyword_search, add missing methods to README [closed]

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