feat: improve OpenAPI request contracts and examples (#418)

* feat: improve OpenAPI request contracts and examples

* fix: align AJV docs plugin typing

* fix: preserve runtime behavior for OpenAPI schemas

* fix: align medication OpenAPI body schema with app payloads

backend/src/utils/documentation-schema-keywords.ts

@@ -0,0 +1,10 @@
+import type { Plugin } from "ajv";
+
+export const registerDocumentationSchemaKeywords: Plugin<unknown> = (ajv) => {
+	ajv.addKeyword({ keyword: "example", valid: true });
+	return ajv;
+};
+
+export const documentationSchemaAjv = {
+	plugins: [registerDocumentationSchemaKeywords],
+};