fix: pre-install OnlyOffice assets during build

Bake OnlyOffice assets into the image to prevent historyKeeper
timeout crash loop caused by lengthy extraction at container startup.

Author: gcordalis

Dockerfile

@@ -9,3 +9,6 @@ RUN git clone https://github.com/cryptpad/sso/
 
 # Revert working directory to the root of the cryptpad project
 WORKDIR /cryptpad
+
+# Pre-install OnlyOffice assets during build to avoid timeout on startup
+RUN ./install-onlyoffice.sh