feat: add SEP-1034 conformance test for elicitation defaults (#14)

Add comprehensive conformance test for SEP-1034 which extends MCP
elicitation to support default values across all primitive types.

Changes:
- Add test_elicitation_sep1034_defaults tool to reference server
- Create ElicitationDefaultsScenario with 5 granular checks:
  * String schema default value
  * Integer schema default value
  * Number schema default value
  * Enum schema default value (validates it's a valid enum member)
  * Boolean schema default value (regression test)
- Register scenario in index.ts

The test validates that servers properly include default values in
elicitation requestedSchema per SEP-1034 specification.

Test results: All 5 checks pass against TypeScript reference server

src/scenarios/index.ts

@@ -26,6 +26,8 @@ import {
   ToolsCallEmbeddedResourceScenario
 } from './server/tools.js';
 
+import { ElicitationDefaultsScenario } from './server/elicitation-defaults.js';
+
 import {
   ResourcesListScenario,
   ResourcesReadTextScenario,
@@ -71,6 +73,9 @@ export const clientScenarios = new Map<string, ClientScenario>([
   ['tools-call-sampling', new ToolsCallSamplingScenario()],
   ['tools-call-elicitation', new ToolsCallElicitationScenario()],
 
+  // Elicitation scenarios (SEP-1034)
+  ['elicitation-sep1034-defaults', new ElicitationDefaultsScenario()],
+
   // Resources scenarios
   ['resources-list', new ResourcesListScenario()],
   ['resources-read-text', new ResourcesReadTextScenario()],