fix(health-check): treat env var errors from executor 500 responses as HEALTHY

The executor returns HTTP 500 for all tool errors, including missing env vars.
Before: 500 response = BROKEN
After: Check error message for env/validation patterns before marking BROKEN

This ensures tools that require API keys (like @parallel-web/ai-sdk-tools)
show importHealth: HEALTHY since the tool loads correctly - it just needs config.

apps/playground/next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/dev/types/routes.d.ts";
+import "./.next/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

apps/web/src/lib/health-check/health-check-service.ts

@@ -136,13 +136,17 @@ async function checkExecutionHealth(tool: Tool & { package: Package }): Promise<
       return { status: 'HEALTHY', error: null, timeMs, testParams };
     }
 
-    // HTTP error from executor itself (not from tool)
-    // This could be executor down, rate limited, etc.
+    // HTTP error from executor - could be tool-level or infrastructure
     const data = await response.json().catch(() => ({}));
     const error = data.error || `HTTP ${response.status}`;
 
-    // Even HTTP errors might be tool-level errors returned through executor
-    // Only mark as BROKEN for true infrastructure failures
+    // Check if this is a config/validation error (tool is working, just missing setup)
+    // The executor returns 500 for all tool errors, so we need to inspect the message
+    if (isNonBreakingError(error)) {
+      return { status: 'HEALTHY', error: null, timeMs, testParams };
+    }
+
+    // True infrastructure failures (executor down, rate limited, etc.)
     if (response.status >= 500) {
       return { status: 'BROKEN', error, timeMs, testParams };
     }