remove: Delete incorrect Dockerfile from root

Workflow uses src/BackOffice/Dockerfile which is correct.
Root Dockerfile was using wrong runtime (aspnet instead of nginx).

Dockerfile

@@ -1,38 +0,0 @@
-FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
-WORKDIR /src
-
-# Copy project file
-COPY src/BackOffice/BackOffice.csproj ./BackOffice/
-COPY src/BackOffice/NuGet.config ./BackOffice/
-
-# Restore dependencies
-RUN dotnet restore "BackOffice/BackOffice.csproj" --configfile BackOffice/NuGet.config
-
-# Copy source code
-COPY src/BackOffice/ ./BackOffice/
-
-# Build and publish
-WORKDIR "/src/BackOffice"
-RUN dotnet publish "BackOffice.csproj" -c Release -o /app/publish
-
-# Runtime stage - nginx for Blazor WASM
-FROM nginx:alpine AS final
-WORKDIR /usr/share/nginx/html
-
-# Copy published wwwroot
-COPY --from=build /app/publish/wwwroot .
-
-# Configure nginx for SPA routing
-RUN cat > /etc/nginx/conf.d/default.conf << 'NGINX_CONF'
-server {
-    listen 80;
-    server_name _;
-    
-    location / {
-        root /usr/share/nginx/html;
-        try_files $uri $uri/ /index.html;
-    }
-}
-NGINX_CONF
-
-EXPOSE 80