Do not mistake a grouping node for a schema because of a child's name

[kudima03]

Closes #46

Cause

CollectDefinitions told a grouping node apart from a schema node by the names of the child keys:

if (child.Any(p => SchemaKeywords.Contains(p.Key)))
{
    result[path] = child;                      // leaf — a schema
}
else
{
    CollectDefinitions(child, path, result);   // group — recurse
}

Specification node names share a namespace with JSON Schema keywords. The booleanOperations group holds or, and and not — and the single not key was enough for Any(...) to return true and for the whole group to be taken for a schema. No recursion happened, so its three members were never emitted.

Beyond the dangling refs this also produced a semantically wrong component: booleanOperations landed in the document as a schema, Microsoft.OpenApi took the not key for the keyword of the same name, and and and or ended up in unrecognizedKeywords.

What changed

A node is now checked first for children that are targets of #/definitions/... pointers. Such a node is always a group, no matter what its children are called. The keyword check stays as the fallback for nodes whose members nothing references.

The set of targets is collected by the new CollectDefinitionPointers, which walks the specification once before the main pass.

Components.Schemas is initialised separately: document.Components ??= new OpenApiComponents() already stood next to it, but on a document without a single generated schema Schemas stayed null and the transformer threw a NullReferenceException — which is what made it impossible to call directly from a test.

Result on the real specification

	before	after
Schemas in the document	160	162
Dangling refs	3	0
booleanOperations as a schema	yes	no
booleanOperations_and/_or/_not	no	yes

Nothing else moved: no existing schema disappeared or changed its contents — exactly three missing ones were added and exactly one wrong component was removed.

Tests

The test project held only FakeTest, so these are the first real tests, written against a minimal specification that reproduces the name collision:

• EmitsMembersOfGroupNamedLikeSchemaKeyword (a Theory over the three members of the group)
• DoesNotEmitGroupingNodeAsSchema
• LeavesNoDanglingComponentReferences — serialises the document and checks that every $ref resolves

Verified that the tests are not vacuous: with the fix reverted all five fail, with the fix all six pass. Every CI step was run locally — dotnet build -warnaserror, dotnet format --verify-no-changes, csharpier check ., dotnet test.

🤖 Generated with Claude Code

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
PureQL.CSharp.Model.OpenAPI.Schema	26%	19%	282	➖
Summary	26% (137 / 519)	19% (51 / 266)	282	➖

Minimum allowed line rate is 0%