chore(changeset): ADR-0058 expression compiler (closes #1887)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: os-zhuang

.changeset/adr-0058-expression-compiler.md

@@ -0,0 +1,16 @@
+---
+"@objectstack/formula": minor
+"@objectstack/plugin-security": minor
+"@objectstack/plugin-sharing": minor
+---
+
+ADR-0058 — expression & predicate surface unification. Adds the canonical
+CEL→FilterCondition pushdown compiler in `@objectstack/formula`
+(`compileCelToFilter`, `isPushdownableCel`, `lowerCelAst`) plus an in-memory
+`matchesFilterCondition` backend (one AST, three backends). `plugin-security`
+(RLS `using`, via a SQL bridge) and `plugin-sharing` (`celToFilter`) cut over to
+it, retiring the bespoke regex/field-equality front-ends. Compound sharing
+conditions now compile and enforce end-to-end (closes #1887). The RLS `check`
+clause is now enforced on the write post-image (insert/by-id update), fail-closed.
+Non-pushdownable predicates (arithmetic, functions, subqueries, cross-object) are
+an authoring compile error, never silently dropped (ADR-0049/0055).