Add database initialization

Runs fieldpoc with `--init` if there are no tables in the database.

nix/modules/fieldpoc.nix

@@ -78,6 +78,10 @@ in {
         if [ ! -f "/var/lib/fieldpoc/extensions.json" ]; then
           echo '{"extensions": {}}' > /var/lib/fieldpoc/extensions.json
         fi
+
+        if [ $(${config.services.postgresql.finalPackage}/bin/psql -q -t -A -c "select count(*) from information_schema.tables where table_schema='fieldpoc';") -eq 0 ]; then
+          ${pkgs.fieldpoc}/bin/fieldpoc -c /run/fieldpoc/config.json --debug --init
+        fi
       '';
     };