test: add property-based tests for AND/OR/NOT composition laws

[rasuvaeff]

Summary

• Adds tests/Integration/CompositionLawsPropertyTest.php: 8 property-based
  tests (rasuvaeff/property-testing) covering the composition algebra —
  andIsCommutative, andIsAssociative, orIsCommutative,
  orIsAssociative, andIsIdempotent, deMorganAnd, deMorganOr,
  distributive.
• Laws are compared semantically: two specification trees are applied via
  QueryApplier to a fresh in-memory SQLite query against a fixed seeded
  items table, and the resulting row-id sets are compared. The package has
  no toSql()/getParameters() — this is the only way to compare trees for
  equivalence.
• Operands are drawn from a pool of 10 ComparisonSpecification leaves
  covering every column/operator shape in the table, optionally wrapped in
  NotSpecification (Gen::recursive, equal odds) to also exercise the
  negated-operand subquery path.

Fixes #20 (part of the monorepo-wide TESTING-STRENGTHENING-PLAN.md §1.1).

Verification

• Sanity check: temporarily made QueryBuildingVisitor::visitNot() a no-op —
  deMorganAnd, deMorganOr and distributive all failed with shrunk
  counterexamples; reverted before committing.
• composer build green (validate → normalize → require-checker → cs →
  psalm → 258 tests, 2518 assertions, including the new 8 properties in the
  Integration suite).

Test plan

• composer build passes
• New properties falsify when NOT handling is broken