feat: Add build date functionality and enhance documentation pages

- Added a script to save the build date during Docker image build.
- Introduced a build_date property in the Settings class to retrieve the build date from the environment or file.
- Enhanced the homepage to display system statistics including processed files and active integrations.
- Updated the about page with a comprehensive list of features.
- Added new privacy, imprint, cookies, and terms pages with relevant content.
- Improved the license page with related information links.
- Refactored the base template for better mobile responsiveness and footer links.

docker/build-scripts/save-build-date.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# Get current date in Month DD, YYYY format (e.g., May 15, 2024)
+BUILD_DATE=$(date +"%B %d, %Y")
+
+# Save it to the BUILD_DATE file
+echo $BUILD_DATE > /app/BUILD_DATE
+
+# Also set it as an environment variable
+echo "Setting BUILD_DATE=$BUILD_DATE"
+export BUILD_DATE