SQLite + sqlite-vec implementation of MnemosyneEcto.Adapter.
Stores embeddings as float32 blobs in a regular table (float[N] column),
performs KNN via sqlite-vec's vec_distance_cosine/2 with an ORDER BY
brute-force scan (which honours the tenant/repo/type SQL filters), and tracks
the migrated schema version in a dedicated <prefix>schema_version table.
The sqlite-vec extension must be loaded on every connection via the repo's
:load_extensions option, e.g.
config :my_app, MyApp.Repo,
adapter: Ecto.Adapters.SQLite3,
load_extensions: [SqliteVec.path()]