Add specifications for gamification, generation, and R42 chat services

- Introduced gamification service spec detailing responsibilities, API surface, XP calculation, levels, streaks, badges, milestone cards, and heatmap data.
- Added generation service spec outlining the process for generating micro learning content, including API endpoints, AI call configuration, prompt strategies, and error handling.
- Created R42 chat service spec covering chatbot interactions, retrieval pipeline, prompt construction, response generation, and stateless design principles.

app/services/ingestion/test-files/payload_md.json

@@ -0,0 +1,6 @@
+{
+  "documentId": "i9ue488qb30owl4",
+  "filename": "sample.md",
+  "format": "md",
+  "filePath": "C:\\Users\\RaymondVerhoef\\Gitea\\learning-platform\\app\\services\\ingestion\\test-files\\sample.md"
+}