include tzdata to avoid time zone issues

Dockerfile

@@ -1,4 +1,10 @@
 FROM mcr.microsoft.com/dotnet/runtime:10.0 AS base
+
+# Install timezone data so .NET can resolve local time zones
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends tzdata \
+    && rm -rf /var/lib/apt/lists/*
+
 USER 1000
 WORKDIR /app
 
@@ -8,7 +14,6 @@ WORKDIR /src
 COPY ["FtpThing.csproj", "./"]
 RUN dotnet restore "FtpThing.csproj"
 COPY . .
-WORKDIR "/src/"
 RUN dotnet build "./FtpThing.csproj" -c $BUILD_CONFIGURATION -o /app/build
 
 FROM build AS publish