fix: reorder JSON structure examples for correct execution

DESCRIBE must come after CREATE (was referencing non-existent structure).
Add CREATE MODULE MyModule setup and DROP MODULE cleanup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: engalar

mdl-examples/doctype-tests/20-json-structure-examples.mdl

@@ -2,14 +2,18 @@
 -- JSON Structure Examples
 -- =============================================================================
 
--- List all JSON structures in the project
+-- MARK: Setup
+CREATE MODULE MyModule;
+
+-- MARK: Show (empty)
+
+-- List all JSON structures in the project (empty initially)
 SHOW JSON STRUCTURES;
 
 -- List JSON structures in a specific module
 SHOW JSON STRUCTURES IN MyModule;
 
--- Describe a JSON structure (shows element tree + JSON snippet)
-DESCRIBE JSON STRUCTURE MyModule.CustomerResponse;
+-- MARK: Create
 
 -- Create a JSON structure from a JSON snippet (single-line)
 CREATE JSON STRUCTURE MyModule.SimpleItem SNIPPET '{"id": 1, "name": "John", "active": true}';
@@ -43,6 +47,13 @@ CUSTOM NAME MAP (
   'naam' AS 'CompanyName'
 );
 
+-- MARK: Describe
+
+-- Describe a JSON structure (shows element tree + JSON snippet)
+DESCRIBE JSON STRUCTURE MyModule.CustomerResponse;
+
+-- MARK: Replace
+
 -- Edit (replace) an existing JSON structure with an updated schema
 CREATE OR REPLACE JSON STRUCTURE MyModule.CustomerResponse SNIPPET $${
   "id": 1,
@@ -61,6 +72,8 @@ CREATE OR REPLACE JSON STRUCTURE MyModule.CustomerResponse SNIPPET $${
   "tags": ["premium", "verified"]
 }$$;
 
+-- MARK: Drop
+
 -- Delete JSON structures
 DROP JSON STRUCTURE MyModule.SimpleItem;
 
@@ -69,3 +82,6 @@ DROP JSON STRUCTURE MyModule.ApiError;
 DROP JSON STRUCTURE MyModule.ExternalApi;
 
 DROP JSON STRUCTURE MyModule.CustomerResponse;
+
+-- MARK: Cleanup
+DROP MODULE MyModule;