Add Polaris FastAPI backend: models/schemas, pricing+scoring+order router, importer, Celery tasks, API routers, seed script

backend/app/main.py

@@ -0,0 +1,38 @@
+"""Polaris FastAPI application.
+
+CORS allow-all (MVP). Routers mounted under /api exactly as the contract lists.
+"""
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.database import Base, engine
+from app.routers import admin, analytics, auth, customers, health, orders, products, suppliers
+from app.version import VERSION
+
+# Idempotent — schema.sql is canonical and already applied; create_all only
+# creates anything missing.
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(title="Polaris API", version=VERSION)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(health.router, prefix="/api", tags=["health"])
+app.include_router(auth.router, prefix="/api/auth", tags=["auth"])
+app.include_router(products.router, prefix="/api/products", tags=["products"])
+app.include_router(suppliers.router, prefix="/api/suppliers", tags=["suppliers"])
+app.include_router(orders.router, prefix="/api/orders", tags=["orders"])
+app.include_router(customers.router, prefix="/api/customers", tags=["customers"])
+app.include_router(admin.router, prefix="/api/admin", tags=["admin"])
+app.include_router(analytics.router, prefix="/api/analytics", tags=["analytics"])
+
+
+@app.get("/")
+def root():
+    return {"app": "polaris", "version": VERSION, "docs": "/docs"}