Step 3: Add admin API endpoints for pricing configuration

- Add PricingConfigResponse and PricingConfigUpdate schemas
- Create PricingService with validation logic
- Add GET and PUT endpoints in routes/pricing.py
- Add MANAGE_PRICING permission to admin role
- Register pricing router in main.py
- Add comprehensive API tests for permissions and validation

backend/routes/pricing.py

@@ -0,0 +1,33 @@
+"""Pricing routes for admin to manage pricing configuration."""
+
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from auth import require_permission
+from database import get_db
+from models import Permission, User
+from schemas import PricingConfigResponse, PricingConfigUpdate
+from services.pricing import PricingService
+
+router = APIRouter(prefix="/api/admin/pricing", tags=["pricing"])
+
+
+@router.get("", response_model=PricingConfigResponse)
+async def get_pricing_config(
+    db: AsyncSession = Depends(get_db),
+    _current_user: User = Depends(require_permission(Permission.MANAGE_PRICING)),
+) -> PricingConfigResponse:
+    """Get current pricing configuration."""
+    service = PricingService(db)
+    return await service.get_config()
+
+
+@router.put("", response_model=PricingConfigResponse)
+async def update_pricing_config(
+    request: PricingConfigUpdate,
+    db: AsyncSession = Depends(get_db),
+    _current_user: User = Depends(require_permission(Permission.MANAGE_PRICING)),
+) -> PricingConfigResponse:
+    """Update pricing configuration."""
+    service = PricingService(db)
+    return await service.update_config(request)