Correct cloud-init.sh usage instructions for real provider UIs

IONOS's User Data field takes a Script Type choice (Cloud Config vs Shell
Script) and runs the pasted/imported content directly rather than fetching
a URL. Update the README to say so, add DEBIAN_FRONTEND=noninteractive for
genuine unattended cloud-init execution.

README.md

@@ -37,10 +37,17 @@ Use a fine-grained read-only PAT scoped to just this repo (Contents: Read).
 **Cloud provider install-script / user-data field (IONOS, DigitalOcean,
 Hetzner, ...):** these run as root with no terminal attached while the
 image is still being provisioned, so `bootstrap.sh`'s interactive hand-off
-doesn't apply yet. Paste `cloud-init.sh` into that field instead:
-```
-https://raw.githubusercontent.com/outis1one/ubuntu-post-install/main/cloud-init.sh
-```
+doesn't apply yet. Use `cloud-init.sh` instead — it's a plain cloud-init
+user-data shell script (starts with `#!/bin/bash`, no `#cloud-config` YAML).
+
+IONOS's server-creation screen has a **User Data** box under "Scripts" with
+a **Script Type** choice of *Cloud Config* or *Shell Script* — pick
+**Shell Script**, then either click **Import from file** and select
+`cloud-init.sh`, or paste its contents directly. User-data fields run the
+script's own content; they don't fetch a URL, so paste/import the file
+itself rather than a link to it. (DigitalOcean/Hetzner's plain "User data"
+textbox works the same way — paste the script contents in directly.)
+
 It clones the repo in the background during provisioning and installs a
 one-shot login hook. The provider boots Ubuntu 24.04, this runs unattended,
 and by the time you SSH in the whiptail service menu is already waiting for

cloud-init.sh

@@ -37,6 +37,7 @@ REPO_URL="https://github.com/outis1one/ubuntu-post-install.git"
 DEST="/root/ubuntu-post-install"
 MARKER="/root/.ubuntu-post-install-pending"
 HOOK="/etc/profile.d/99-ubuntu-post-install.sh"
+export DEBIAN_FRONTEND=noninteractive
 
 command -v git >/dev/null 2>&1 || { apt-get update -qq && apt-get install -y git; }