Add Pitopn digital shop with FastAPI, Postgres 17, and Docker Compose

Co-authored-by: Cursor <cursoragent@cursor.com>

app/main.py

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+import time
+from contextlib import asynccontextmanager
+from pathlib import Path
+
+from fastapi import Depends, FastAPI, Request
+from fastapi.responses import HTMLResponse
+from fastapi.staticfiles import StaticFiles
+from fastapi.templating import Jinja2Templates
+from sqlalchemy import select
+from sqlalchemy.exc import OperationalError
+from sqlalchemy.orm import Session
+
+from app.config import get_settings
+from app.database import Base, engine, get_db
+from app.models import Category, Product
+from app.seed import seed_if_empty
+
+BASE_DIR = Path(__file__).resolve().parent
+settings = get_settings()
+
+
+def wait_for_db(retries: int = 30, delay: float = 1.0) -> None:
+    for attempt in range(1, retries + 1):
+        try:
+            with engine.connect() as conn:
+                conn.exec_driver_sql("SELECT 1")
+            return
+        except OperationalError:
+            if attempt == retries:
+                raise
+            time.sleep(delay)
+
+
+@asynccontextmanager
+async def lifespan(_: FastAPI):
+    wait_for_db()
+    Base.metadata.create_all(bind=engine)
+    from app.database import SessionLocal
+
+    db = SessionLocal()
+    try:
+        seed_if_empty(db)
+    finally:
+        db.close()
+    yield
+
+
+app = FastAPI(title=settings.app_name, lifespan=lifespan)
+app.mount("/static", StaticFiles(directory=BASE_DIR / "static"), name="static")
+templates = Jinja2Templates(directory=str(BASE_DIR / "templates"))
+
+
+def format_price(value) -> str:
+    try:
+        amount = float(value)
+    except (TypeError, ValueError):
+        return str(value)
+    formatted = f"{amount:,.0f}".replace(",", " ")
+    return f"{formatted} ₽"
+
+
+templates.env.filters["rub"] = format_price
+
+
+@app.get("/health")
+def health() -> dict[str, str]:
+    return {"status": "ok"}
+
+
+@app.get("/", response_class=HTMLResponse)
+def home(request: Request, db: Session = Depends(get_db)):
+    categories = db.scalars(
+        select(Category).order_by(Category.sort_order, Category.name)
+    ).all()
+    featured = db.scalars(
+        select(Product)
+        .where(Product.is_active.is_(True), Product.is_featured.is_(True))
+        .order_by(Product.id)
+        .limit(4)
+    ).all()
+    products = db.scalars(
+        select(Product)
+        .where(Product.is_active.is_(True))
+        .order_by(Product.is_featured.desc(), Product.id)
+        .limit(12)
+    ).all()
+
+    return templates.TemplateResponse(
+        request,
+        "index.html",
+        {
+            "app_name": settings.app_name,
+            "categories": categories,
+            "featured": featured,
+            "products": products,
+        },
+    )