feat: use structuredContent with outputSchema in example servers (#220)

* build app-with-deps

* make registerAppTool more interchangeable w/ server.registerTool

* feat: use structuredContent in all example servers

All servers now return structuredContent alongside JSON text content.
All mcp-apps now read structuredContent directly (no JSON.parse fallback).

Updated servers:
- basic-server-vanillajs
- budget-allocator-server
- cohort-heatmap-server
- customer-segmentation-server
- integration-server
- scenario-modeler-server
- system-monitor-server
- threejs-server
- video-resource-server
- wiki-explorer-server

* feat: add outputSchema to all example servers

Define output schemas for structuredContent validation:
- basic-server-vanillajs: { time: string }
- budget-allocator-server: BudgetDataResponseSchema
- cohort-heatmap-server: CohortDataSchema
- customer-segmentation-server: customers/segments schema
- integration-server: { time: string }
- scenario-modeler-server: templates/defaultInputs schema
- system-monitor-server: SystemStatsSchema
- threejs-server: { code, height }
- video-resource-server: { videoUri, description }
- wiki-explorer-server: { page, links, error }

* prettier:fix

* make registerAppTool more interchangeable w/ server.registerTool

* feat: use structuredContent in all example servers

All servers now return structuredContent alongside JSON text content.
All mcp-apps now read structuredContent directly (no JSON.parse fallback).

Updated servers:
- basic-server-vanillajs
- budget-allocator-server
- cohort-heatmap-server
- customer-segmentation-server
- integration-server
- scenario-modeler-server
- system-monitor-server
- threejs-server
- video-resource-server
- wiki-explorer-server

* feat: add outputSchema to all example servers

Define output schemas for structuredContent validation:
- basic-server-vanillajs: { time: string }
- budget-allocator-server: BudgetDataResponseSchema
- cohort-heatmap-server: CohortDataSchema
- customer-segmentation-server: customers/segments schema
- integration-server: { time: string }
- scenario-modeler-server: templates/defaultInputs schema
- system-monitor-server: SystemStatsSchema
- threejs-server: { code, height }
- video-resource-server: { videoUri, description }
- wiki-explorer-server: { page, links, error }

* prettier:fix

* revert: remove unrelated workflow, version, and arch changes

* chore: update package-lock.json

* refactor(basic-server-vanillajs): address PR review comments

- Simplify server.ts to return plain time string in text content (not JSON),
  matching the quickstart guide pattern
- Add defensive coding in mcp-app.ts with optional chaining and fallback
  to handle potential type mismatches gracefully

* refactor: restore rich text formatting for LLM-readable content

Restore the human-readable text formatting functions that were removed,
providing meaningful summaries in the text content while keeping
structuredContent for programmatic UI consumption:

- budget-allocator-server: formatBudgetSummary with config overview
- cohort-heatmap-server: formatCohortSummary with retention stats
- scenario-modeler-server: formatScenarioSummary with financial metrics

examples/cohort-heatmap-server/server.ts

@@ -152,6 +152,17 @@ function generateCohortData(
   };
 }
 
+function formatCohortSummary(data: CohortData): string {
+  const avgRetention = data.cohorts
+    .flatMap((c) => c.cells)
+    .filter((cell) => cell.periodIndex > 0)
+    .reduce((sum, cell, _, arr) => sum + cell.retention / arr.length, 0);
+
+  return `Cohort Analysis: ${data.cohorts.length} cohorts, ${data.periods.length} periods
+Average retention: ${(avgRetention * 100).toFixed(1)}%
+Metric: ${data.metric}, Period: ${data.periodType}`;
+}
+
 export function createServer(): McpServer {
   const server = new McpServer({
     name: "Cohort Heatmap Server",
@@ -169,6 +180,7 @@ export function createServer(): McpServer {
       description:
         "Returns cohort retention heatmap data showing customer retention over time by signup month",
       inputSchema: GetCohortDataInputSchema.shape,
+      outputSchema: CohortDataSchema.shape,
       _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
     },
     async ({ metric, periodType, cohortCount, maxPeriods }) => {
@@ -180,7 +192,8 @@ export function createServer(): McpServer {
       );
 
       return {
-        content: [{ type: "text", text: JSON.stringify(data) }],
+        content: [{ type: "text", text: formatCohortSummary(data) }],
+        structuredContent: data,
       };
     },
   );