feat: Improve payment modal logic and Docker configuration

Refactor the family detail page to introduce a new `handleOpenAddModal` function. This function intelligently sets the default payment method based on the current user's role: 'manual' for admins/power users and 'paypal' for others. This enhances user experience by pre-selecting the most appropriate payment option.

Additionally, the Docker configuration files have been updated. The mult-stage build setup for the frontend and backend has been removed in favor of a simpler structure, streamlining the Docker build process. The `nginx.conf` has also been updated to reflect these changes and ensure proper proxying.

Dockerfile

@@ -1,14 +0,0 @@
-# Stage 1: Build Frontend
-FROM node:18-alpine as build
-WORKDIR /app
-COPY package*.json ./
-RUN npm install
-COPY . .
-RUN npm run build
-
-# Stage 2: Serve with Nginx
-FROM nginx:alpine
-COPY --from=build /app/dist /usr/share/nginx/html
-COPY nginx.conf /etc/nginx/nginx.conf
-EXPOSE 80
-CMD ["nginx", "-g", "daemon off;"]