chore: Halkyon Todo's scaffold joins the repository in apps/todo

Its server, client and app as `serverpod create` made them, with the
switch to server-side sessions that was waiting uncommitted, as files:
its one commit holds the scaffold alone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_server/Dockerfile

@@ -0,0 +1,58 @@
+# Build from the project root with:
+# docker build -f halkyon_todo_server/Dockerfile .
+
+# Build stage
+FROM dart:3.12.2 AS build
+
+# Create a minimal workspace that preserves locked server dependency versions.
+WORKDIR /app
+COPY pubspec.lock .
+COPY halkyon_todo_server halkyon_todo_server
+RUN printf '%s\n' \
+  'name: _' \
+  'environment:' \
+  '  sdk: ^3.12.2' \
+  'workspace:' \
+  '  - halkyon_todo_server' \
+  > pubspec.yaml
+RUN dart pub get
+
+# Compile the server executable.
+WORKDIR /app/halkyon_todo_server
+RUN dart build cli --target bin/main.dart --output build
+RUN mv build/bundle/bin/main build/bundle/bin/server
+
+# Add a fallback for the copy of possibly missing directories.
+RUN mkdir -p config web migrations
+
+# Final stage
+FROM alpine:latest
+WORKDIR /app
+
+# Environment variables
+ENV runmode=production
+ENV serverid=default
+ENV logging=normal
+ENV role=monolith
+
+# Copy runtime dependencies
+COPY --from=build /runtime/ /
+
+# Copy compiled server executable and native libraries
+COPY --from=build /app/halkyon_todo_server/build/bundle/ ./
+
+# Copy configuration files and resources
+COPY --from=build /app/halkyon_todo_server/config/ config/
+COPY --from=build /app/halkyon_todo_server/web/ web/
+COPY --from=build /app/halkyon_todo_server/migrations/ migrations/
+
+# This file is required to enable the endpoint log filter in Insights.
+COPY --from=build /app/halkyon_todo_server/lib/src/generated/protocol.yaml lib/src/generated/protocol.yaml
+
+# Expose ports
+EXPOSE 8080
+EXPOSE 8081
+EXPOSE 8082
+
+# Define the entrypoint command
+ENTRYPOINT ./bin/server --mode=$runmode --server-id=$serverid --logging=$logging --role=$role