Brushed up the backend, added writing task 1 academic prompt gen and grading ENCOA-274

ielts_be/utils/image_to_b64.py

@@ -0,0 +1,10 @@
+def _b64_vision_images(path: str):
+    for filename in os.listdir(path):
+        if filename.startswith("cv-") and filename.endswith(".png"):
+            cv_dict.append({
+              "type": "image_url",
+              "image_url": {
+                "url": f"data:image/png;base64,{_encode_image(os.path.join(path, filename))}"
+              }
+            })
+    return cv_dict