Support the predicate expressions CoreData can represent

[colemancda]

Follow-up to #34 (which merged the base Foundation.Predicate conversion), extending both the predicate model and the in-memory evaluator to cover the expressions CoreData can represent.

Arithmetic

• New FetchRequest.Predicate.ArithmeticExpression (add/subtract/multiply/divide/modulus) as an Expression case, with Codable support. Its raw values are the corresponding NSExpression function names, so CoreDataModel bridges them directly via NSExpression(forFunction:).
• In-memory evaluation: integer operands stay integral, so division truncates exactly as Swift's / and NSExpression's divide:by: both do (7 / 2 is 3); division or remainder by zero, overflowing division, floating-point remainder, and non-numeric operands resolve to no match rather than trapping.
• #Predicate converts +, -, *, /, %, and unary minus (lowered to * -1, as NSExpression has no negation function).

Collections, aggregates and ranges

• allSatisfy { ... } and contains(where:) { ... } convert to ALL/ANY modifier comparisons. Those nodes bind their own element variable, so conversions now thread a context mapping each predicate variable to its key path.
• min() / max() convert to @min / @max key path operators.
• Half-open ranges (18..<30) convert alongside closed ones, lowered to comparisons since BETWEEN isn't evaluatable.

Regex

• contains(regex) converts to a MATCHES comparison. The macro wraps regexes in PredicateExpressions.PredicateRegex, which retains the source pattern, so regex literals, Regex(String), and RegexBuilder regexes all convert. The pattern is padded with .* because MATCHES matches the whole value rather than a substring, matching Foundation's own conversion. Requires macOS 15 / iOS 18, where those types are available.

Relationship key path traversal (bug fix)

Key paths that traverse a relationship (events.name) previously resolved to nothing in the in-memory evaluator, so every ALL/ANY predicate silently matched zero objects while the identical predicate returned the correct rows through CoreData. The evaluator now resolves to-one and to-many relationships against an object index: FetchRequest.evaluate(_:) builds the index from the objects it is given, and InMemoryStorage supplies every entity's objects so relationships resolve.

Tests

• ArithmeticExpressionTests: construction, description, Codable round-trip, evaluation semantics, fetch request evaluation.
• FoundationPredicateTests: every supported expression shape, converted-tree assertions, in-memory filtering, and error paths.
• KeyPathTraversalTests: to-one and to-many traversal, ALL/ANY, unresolved relationships, InMemoryStorage fetches, and the same traversals built with #Predicate.
• CoreDataModelTests: end-to-end CoreData fetches for arithmetic, ALL/ANY, and regex predicates built both from #Predicate and the CoreModel API — including a check that empty to-many ALL is vacuously true in CoreData and that the in-memory evaluator agrees on the same objects.

161 tests pass, including the Embedded WebAssembly build (the object index is built without dynamic casting, which Embedded Swift forbids).

[github-code-quality]

Code Coverage Overview

Languages: Swift

Swift / code-coverage/llvm-cov

The overall coverage in commit 5b11022 in the feature/predicate branch is 94%. The coverage in commit ea30b8b in the master branch is 95%.

Show a code coverage summary of the most impacted files.

File	master ea30b8b	feature/predicate 5b11022	+/-
Sources/CoreMod.../Evaluate.swift	96%	95%	-1%
Sources/CoreMod...ryStorage.swift	92%	92%	0%
Sources/CoreDat...valuation.swift	100%	100%	0%
Sources/CoreDat...Predicate.swift	100%	100%	0%
Sources/CoreMod...valuation.swift	100%	100%	0%
Sources/CoreMod...xpression.swift	100%	100%	0%
Sources/CoreMod...Predicate.swift	85%	89%	+4%
Sources/CoreMod...xpression.swift	0%	100%	+100%