fix(embedded): convert the Value variants 0.5 added

Bumping coordinode-rs to the v0.5.1 release grew the core Value enum, and the
binding matched it non-exhaustively:

  error[E0004]: non-exhaustive patterns: `Value::MultiVector(_)` and
  `Value::Path(_)` not covered

MultiVector carries token-level embeddings and is exposed as a list of float
rows, the way a single Vector already is. Path carries the node and
relationship sequence that shortestPath and variable-length MATCH produce; it
becomes a dict of `nodes` and `rels`, mirroring the msgpack shape the server
puts on the wire so both surfaces read the same.

Cargo.lock moves with the submodule, and the crate is formatted.

Author: polaz