Adopt mcp-kit 0.3 and delete shared implementations

[shtse8]

Outcome

Use the published sylphx-mcp-kit 0.3.0 for embeddings, lexical tokenization, star hints and cache roots. Delete local embed.rs, tokenize.rs and star_hint.rs and the cache-root implementation.

Compatibility

Ranking, model choice, opt-out, mirror URL and LOCKDOCS_CACHE layout remain product-owned. semantic.rs is only policy/loading orchestration; all model parsing, downloading, tokenization, quantization and cosine math live upstream. Identifier mode preserves old vectors. Existing model.q8/vocab.txt load directly; persisted Vec8 postcard fields are unchanged and have a compatibility test. No cache format bump or rebuild is needed. Public embed/tokenize module names remain aliases.

Validation

Selected-source rustfmt check, git diff --check, manifest-version check and capability-path check passed. Cargo lockfile resolved the published registry release. No local Rust compiles; full cross-platform CI and the benchmark run in GitHub Actions.

Built by: GPT-6.1. Review: pending

[shtse8]

Final-head CI and benchmark run 36793151470 are green. Read back bench.json: fetched 96/105 (866 median tokens, 80.2 ms median), package-only hybrid 60/105 (903 median tokens, 30.8 ms median). Both accuracy gates hold; ranking was not changed.