Add Image models and clean up test code structure

Introduced `ImageCreate` and `Image` models to handle image-related data in the backend. Improved the organization and readability of the testing notebook by consolidating and formatting code into distinct sections with markdown cells.

backend/main.py

@@ -4,6 +4,7 @@ import tomllib
 from pathlib import Path
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.staticfiles import StaticFiles
 from app import ssl_heidi
 from app.routers import (
     proposal,
@@ -159,6 +160,9 @@ app.include_router(spreadsheet.router, tags=["spreadsheet"])
 app.include_router(logistics.router, prefix="/logistics", tags=["logistics"])
 app.include_router(sample.router, prefix="/samples", tags=["samples"])
 
+app.mount("/images", StaticFiles(directory="images"), name="images")
+
+
 if __name__ == "__main__":
     import sys
     from dotenv import load_dotenv