feat(import): resolve references and schema composition

crates/crank-import/src/rest/schema.rs

@@ -32,8 +32,33 @@ pub fn schema_from_openapi(
     let Some(value) = value else {
         return primitive(SchemaKind::String, required, description);
     };
-    // NormalizedIR keeps composition typed; the legacy preview adapter retains
-    // its historical first-branch projection for pending v1 jobs.
+    // Only v3 NormalizedIR emits the private marker. Pending legacy-v1 jobs
+    // retain their historical first-branch behavior, while modern oneOf/anyOf
+    // is projected losslessly through crank-schema's existing Oneof shape.
+    if value
+        .get("x-crank-lossless-composition")
+        .and_then(Value::as_bool)
+        == Some(true)
+        && let Some(items) = value
+            .get("oneOf")
+            .or_else(|| value.get("anyOf"))
+            .and_then(Value::as_array)
+    {
+        return Schema {
+            kind: SchemaKind::Oneof,
+            description: description.or_else(|| text(value, "description")),
+            required,
+            nullable: nullable(value),
+            default_value: value.get("default").cloned(),
+            fields: BTreeMap::new(),
+            items: None,
+            enum_values: Vec::new(),
+            variants: items
+                .iter()
+                .map(|item| schema_from_openapi(Some(item), true, None))
+                .collect(),
+        };
+    }
     let resolved = collapse_composition(value);
 
     if let Some(values) = resolved.get("enum").and_then(Value::as_array) {