env Example hinzugefpgt

math-tutor/backend/.env-Example

+MATHPIX_APP_ID=""
+MATHPIX_APP_KEY=""
+
+OPENAI_BASE_URL=""
+OPENAI_API_KEY=""
+OPENAI_CHAT_MODEL=""
+OPENAI_EMBED_MODEL=""
+
+POSTGRES_URL=""
+
+OLLAMA_URL=""
+OLLAMA_MODEL= ""
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