Add deployment secrets for active record encryption

which is used by console1984 and audits1984.

ref: https://app.fizzy.do/5986089/cards/2469

saas/Dockerfile

@@ -40,8 +40,12 @@ COPY . .
 # Precompile bootsnap code for faster boot times
 RUN bundle exec bootsnap precompile app/ lib/
 
-# Precompiling assets for production without requiring secret RAILS_MASTER_KEY
-RUN SECRET_KEY_BASE_DUMMY=1 ./bin/rails assets:precompile
+# Precompiling assets for production
+RUN SECRET_KEY_BASE_DUMMY=1 \
+    ACTIVE_RECORD_ENCRYPTION_PRIMARY_KEY=1 \
+    ACTIVE_RECORD_ENCRYPTION_DETERMINISTIC_KEY=1 \
+    ACTIVE_RECORD_ENCRYPTION_KEY_DERIVATION_SALT=1 \
+    ./bin/rails assets:precompile
 
 # Final stage for app image
 FROM base