Add project setup some models and a test

src/allmende_payment_system/app.py

@@ -1,11 +1,16 @@
 # backend/app/main.py
 from fastapi import FastAPI, Request
-from fastapi.templating import Jinja2Templates
 from fastapi.staticfiles import StaticFiles
+from fastapi.templating import Jinja2Templates
 
 app = FastAPI()
 templates = Jinja2Templates(directory="src/allmende_payment_system/templates")
-app.mount("/static", StaticFiles(directory="src/allmende_payment_system/static"), name="static")
+app.mount(
+    "/static",
+    StaticFiles(directory="src/allmende_payment_system/static"),
+    name="static",
+)
+
 
 @app.get("/")
 async def landing_page(request: Request):