replace remaining seq loops with bash arithmetic for

install.sh

@@ -96,7 +96,7 @@ install_docker() {
   if ! $SUDO docker info &>/dev/null; then
     warn "Docker daemon not running — starting..."
     $SUDO systemctl enable --now docker 2>/dev/null || $SUDO dockerd &>/dev/null &
-    for i in $(seq 1 15); do
+    for ((i=1; i<=15; i++)); do
       sleep 2
       if $SUDO docker info &>/dev/null; then
         info "Docker daemon started"
@@ -256,7 +256,7 @@ fi
 
 info "Waiting for PostgreSQL (up to 60s)..."
 DB_READY=false
-for i in $(seq 1 30); do
+for ((i=1; i<=30; i++)); do
   if $SUDO docker compose exec -T postgres pg_isready -U "${POSTGRES_USER}" -d "${POSTGRES_DB}" &>/dev/null; then
     DB_READY=true
     info "PostgreSQL is ready"