Add comprehensive documentation for employee learning platform

- Created handover document outlining design decisions and application functionality.
- Developed implementation plan detailing phased approach for service development.
- Specified ingestion service responsibilities, API surface, and processing pipeline.

app/services/ingestion/src/lib/anthropic.ts

@@ -0,0 +1,9 @@
+import Anthropic from '@anthropic-ai/sdk';
+
+export const anthropic = new Anthropic({
+  apiKey: process.env['ANTHROPIC_API_KEY'],
+});
+
+export const MODELS = {
+  SONNET: 'claude-sonnet-4-20250514',
+} as const;