fix: configure .env even when .env.example doesn't exist

Release zip contains .env directly, not .env.example. The sed commands
to update database credentials were being skipped because the file check
looked for .env.example first, which doesn't exist in published releases.

scripts/install-ubuntu.sh

@@ -160,6 +160,9 @@ fi
 echo -e "${COLOR_GREEN}[7/9] Configuring OSPOS...${COLOR_RESET}"
 if [ -f ".env.example" ]; then
     cp .env.example .env
+fi
+
+if [ -f ".env" ]; then
     sed -i "s/database\.default\.hostname = localhost/database.default.hostname = ${DB_HOST}/" .env
     sed -i "s/database\.default\.database = ospos/database.default.database = ${DB_NAME}/" .env
     sed -i "s/database\.default\.username = admin/database.default.username = ${DB_USER}/" .env