Customers can view and cancel their booking through a link in the e-mail. Fixes #18

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -33,7 +33,7 @@ RUN LEPTOS_OUTPUT_NAME="rezervator-$(tr -dc a-z0-9 </dev/urandom | head -c 10)"
 FROM debian:bookworm-slim AS runtime
 WORKDIR /app
 RUN apt-get update -y \
-  && apt-get install -y --no-install-recommends openssl ca-certificates \
+  && apt-get install -y --no-install-recommends openssl ca-certificates tzdata \
   && apt-get autoremove -y \
   && apt-get clean -y \
   && rm -rf /var/lib/apt/lists/*
@@ -44,7 +44,7 @@ COPY --from=builder /app/target/release/rezervator /app/
 # /target/site contains our JS/WASM/CSS, etc.
 COPY --from=builder /app/target/site /app/target/site
 
-# Set any required env variables and
+# Bookings are in local time: set TZ (e.g. TZ=Europe/Prague), otherwise the clock is UTC
 EXPOSE 3000
 
 # The config file holds passwords and the session key. Mount it to /app/config, never under