[verified] add upload size and MIME guards

(cherry picked from commit f5e05376f6)

routers/exam/templates.py

@@ -28,6 +28,7 @@ from api.services.docling.regions import detect_response_regions_from_pdf
 from modules.database.services.exam_projection import project_template, project_template_safe
 from modules.database.supabase.utils.client import SupabaseServiceRoleClient
 from modules.database.supabase.utils.storage import StorageAdmin
+from modules.upload_validation import read_pdf_upload_bytes
 from modules.logger_tool import initialise_logger
 from routers.exam.dependencies import ExamContext, get_exam_context, lookup_exam_code
 from routers.exam.schemas import (
@@ -164,11 +165,7 @@ async def _upload_template_source_file(
     institute_id: str,
     upload: UploadFile,
 ) -> str:
-    file_bytes = await upload.read()
-    if not file_bytes:
-        raise HTTPException(status_code=400, detail="Uploaded PDF is empty")
-    if upload.content_type and upload.content_type != "application/pdf":
-        raise HTTPException(status_code=400, detail="Uploaded file must be a PDF")
+    file_bytes = await read_pdf_upload_bytes(upload)
 
     service = SupabaseServiceRoleClient()
     storage = StorageAdmin()