fix(cortex): integrate intake intents into full chat + artifact flow

Fixes 4 bugs preventing intake blocks from working:

1. Chat API validation: Add 'nudge' to message type enum, allow empty
   content for streaming messages
2. AI chat recognition: Add P3 intake intents (intake_status,
   risico_query, diagnose_query, intake_navigeer) to system prompt
   with triggers, entities, and JSON examples
3. Artifact rendering: Add intake block imports and switch cases
   to artifact-container.tsx
4. API 400 error: Convert null to undefined for optional Zod params
   (searchParams.get returns null, Zod .optional() expects undefined)

Also adds:
- Testplan for E2E testing (60+ test cases)
- Session log with lessons learned and new intent checklist

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/cortex/chat-api.ts

@@ -50,6 +50,10 @@ export async function sendChatMessage(
 
     if (!response.ok) {
       const errorData = await response.json().catch(() => ({ error: response.statusText }));
+      // Log validation details for debugging
+      if (errorData.details) {
+        console.error('Validation details:', errorData.details);
+      }
       throw new Error(errorData.error || 'API request failed');
     }
 

lib/cortex/hooks/use-block-data.ts

@@ -95,6 +95,14 @@ export function useBlockData<T>({
       setData(result);
     } catch (err) {
       const statusCode = (err as any)?.statusCode;
+      const details = (err as any)?.details;
+      console.error('[useBlockData] Error:', {
+        operation: operationName,
+        statusCode,
+        message: (err as Error)?.message,
+        details,
+      });
+
       const errorInfo = getErrorInfo(err, {
         operation: operationName,
         statusCode,