Enhance Docker setup with logging and monitoring features

- Added logging configuration to WSGI for persistent log collection.
- Updated Docker Compose files for local and development environments, including Redis, PostgreSQL, and Grafana services.
- Introduced Promtail configuration for log scraping and integration with Loki.
- Created application log directory in Dockerfile for log persistence.

rad/Dockerfile.prod

@@ -57,6 +57,12 @@ ENV PATH="/opt/venv/bin:$PATH"
 # `--chown` flag during COPY and avoid an expensive recursive `chown -R`.
 RUN useradd -m appuser
 
+# Create directory for application logs and ensure ownership is correct.
+# Do this as root before switching to `appuser` so the directory exists
+# and can be mounted by the dev compose override.
+RUN mkdir -p /var/log/rad \
+    && chown -R appuser:appuser /var/log/rad
+
 # Copy project files into image and set ownership during copy (faster than
 # a separate `chown -R` step). This keeps layer reuse efficient.
 COPY --chown=appuser:appuser . /usr/src/app