feat: add nginx config and Dockerfile for Vue frontend

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

BudgetApp.Web/Dockerfile.web

@@ -0,0 +1,13 @@
+# Stage 1: Build Vue app
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY . .
+RUN npm run build-only
+
+# Stage 2: Serve with nginx
+FROM nginx:alpine AS runtime
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY nginx.web.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80

BudgetApp.Web/nginx.web.conf

@@ -0,0 +1,19 @@
+server {
+    listen 80;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Proxy /api/ requests to the API container — prefix preserved
+    location /api/ {
+        proxy_pass http://budgetapp-api:8080;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+
+    # Serve Vue SPA — fallback to index.html for client-side routing
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+}