fix: make QdrantLocal runnable from the web UI

[serhiizghama]

Fixes #796. QdrantLocal can't be run from the web UI at all — QdrantLocalIndexConfig requires m and ef_construct, but there's no DB.QdrantLocal entry in CASE_CONFIG_MAP, so the UI renders "Auto", passes an empty config, and pydantic raises 2 validation errors ... Field required before the run starts. That matches the reporter's "seems like 'ef_construct' is missing, but there is not such option" — the option genuinely isn't there.

Gave both fields the same defaults the CLI already uses (m=16, ef_construct=200) and registered QdrantLocal in CASE_CONFIG_MAP so m, ef_construct and on_disk are tunable for load, plus hnsw_ef for search — the same four knobs qdrant_local/cli.py exposes. Needed two new CaseConfigParamType members since the existing ef_construction spelling doesn't match the model field.

The CLI path is unchanged: it always passed these explicitly. Verified the empty-config case now builds, that the UI defaults round-trip into index_param()/search_param(), and that tuned values reach the client. New tests fail on main and pass here.

[sre-ci-robot]

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