somnia v0.8.0

Completes the P3 roadmap tier: typed authentication, live queries, full-text /
vector search helpers, and SurrealDB 3.x type-system surface (closures,
REFERENCEs, union / literal types). Two small breaking changes: a new
SomniaError::Auth variant (breaks exhaustive matches on SomniaError), and
DefineIndex::search() / #[index(search = …)] now emit FULLTEXT ANALYZER …
instead of the pre-3.x SEARCH ANALYZER … (changed output, same API). Bump your
dependency to somnia = "0.8".

Added

• Authentication (P3). The client grows a typed auth surface beyond
  root-only signin. A Credentials enum (Root / Namespace / Database /
  Token, each with an ergonomic constructor) drives the new
  SomniaClient::connect_with(endpoint, ns, db, creds), and
  connect_anonymous(endpoint, ns, db) connects without signing in (for
  embedded engines or deferred auth). On an existing connection:
  signin(&creds), record/scope auth via signin_record / signup_record
  (params are any Serialize value, flattened into the access method's
  $params), authenticate(token) to attach a pre-issued JWT, and
  invalidate() to clear the session. Signin/signup/record calls return the
  issued access token. Auth failures surface as a new SomniaError::Auth
  variant. Verified end-to-end against the live in-memory engine (record
  signup → signin → invalidate, wrong-password rejection).

• Live queries (P3). SomniaClient::live_select::<T>() starts a LIVE SELECT on T's table and returns a LiveQueryStream<T> — a futures
Stream of Notification<T> carrying the change Action
  (Create/Update/Delete), the originating query_id, and the deserialized
  record. Dropping the stream issues KILL server-side (no explicit teardown).
  Works on the embedded (mem://) engine and over ws://. Verified live
  (create → update → delete notifications with the decoded record).

• Vector / full-text query helpers (P3). Table::search(field, query) → Search<T> builds full-text WHERE field @@ 'query' selects with optional
  search::score projection / relevance ordering; Table::nearest(field, vec) → VectorSearch<T> builds vector KNN selects (<|k,ef|> HNSW or <|k,METRIC|>
  brute force) with vector::distance::knn() projection / nearest-first
  ordering. New composable expression nodes MatchesExpr (@@) and KnnExpr
  (<|…|>), plus Column::matches. Both render to_surrealql[_with_params] and
  are verified live (ranked full-text search, HNSW nearest-neighbour ordering).

• SurrealDB 3.x type-system (P3). A typed Closure expression node renders
  anonymous functions (|$x: int| -> int $x * 2) for higher-order calls /
  computed values. The derive gains #[field(reference)] /
  #[field(reference = "cascade")] to emit record REFERENCE [ON DELETE …].
  Union (#[field(ty = "int | string")]) and literal
  (#[field(ty = "'a' | 'b'")]) field types are confirmed end-to-end. future<T>
  is intentionally omitted — the keyword no longer exists in SurrealDB 3.x.

Changed

• (Fix) DefineIndex::search() / #[index(search = …)] now emit FULLTEXT ANALYZER … instead of the pre-3.x SEARCH ANALYZER …, which SurrealDB 3.x
  rejects as a parse error. The method/attribute names are unchanged; only the
  emitted keyword. Needed for the new full-text query helpers to run against a
  real index.

• README — expanded the terse "More query power" block into descriptive,
  per-feature sections (Parameters & LET, Transactions, Subqueries & IN,
  SELECT modifiers, Control flow, advanced schema DDL, graph edges), each with a
  worked sample and the rendered SurrealQL shown inline.