v0.19.0

v0.19.0 — CASE and operators in the build-time SET dialect

slater-build can now ingest business-key MERGE dumps whose SET right-hand
sides use CASE expressions and infix operators, not just function calls,
literals, and same-node property references.

Highlights

• Build-time SET gains a full scalar-expression grammar: CASE
  (searched and simple), comparison (=, <>, <, <=, >, >=),
  arithmetic and string concatenation (+, -, *, /, %), and
  boolean AND/OR/NOT, with standard precedence and parentheses.
• A common accumulator idiom now builds unmodified, e.g.
  SET n.summary = CASE WHEN coalesce(n.summary,'') = '' THEN x ELSE n.summary + '; ' + x END. Each assignment folds against the node's
  accumulated properties in input order, so the result matches a live graph
  engine's — without the quadratic read-grow-rewrite cost.
• Operator, comparison, and truthiness semantics are shared with the query
  engine through slater-scalar, so build-time and query-time evaluation
  agree (string-concat +, three-valued =/NULL handling, Kleene booleans).
• CASE branches evaluate lazily: only the selected THEN/ELSE runs.

Scope and compatibility

• Edge SET and overlay-patch SET remain literal-only.
• Existing dumps are unaffected; this is strictly a superset of the prior
  dialect.

No configuration changes are required.

Full Changelog: v0.18.0...v0.19.0