make iiab-android proot-safe (deterministic chroot/reboot handling)

[luisguzman-adfa]

Building / running the IIAB installer under proot relies on chroot/container detection that is environment-dependent and unreliable. On a phone it usually resolves "chroot/proot" so the install works; but in headless /
async builds — building the rootfs on an ARM64 board (Rock 5B+), via GitHub Actions, or as a server maintenance routine on iiab.switnet.org — the same checks can flip the other way, and IIAB then attempts systemd / reboot
actions that don't exist under proot, breaking the build at a different spot each time (the "it breaks for any little thing" symptom).

There are three independent detections, at three layers:

1. Ansible fact ansible_facts.is_chroot — gates systemd-only tasks, e.g. roles/0-init/tasks/hostname.yml: command: hostnamectl ... with when: not ansible_facts.is_chroot. Under proot, when the fact is wrongly False, hostnamectl runs and fails (hostnamectl: not found).

   The fact is driven by the debian_chroot env var (or a /proc heuristic).

2. Native /usr/sbin/iiab bash IS_CHROOT — ischroot -t || systemd-detect-virt --container -q. When False, the installer ends with reboot (absent under proot → rc 127), which aborts this wrapper before its Android tail (install_iiaboa_dashboard, readiness flags).

3. Missing binaries under proot: reboot, hostnamectl.

Fixed by,

• (1) Forces ansible_facts.is_chroot = True deterministically: exports debian_chroot, persists it in /etc/environment (pam_env), and keeps it across sudo via /etc/sudoers.d/99-iiab-proot-chroot (Defaults env_keep += "debian_chroot"). install.txt runs the installer via sudo, whose default env_reset would otherwise strip it.
• (2) Installs a proot-correct ischroot (exit 0) and a no-op reboot in /usr/local/sbin, so the native installer takes its IS_CHROOT=true path ("IIAB Done", no reboot, no tty prompt) and the wrapper continues to the Android tail. These are also correct to keep in the rootfs (under proot we are chroot-like and must never drive the host init).
• (3) Safety-net hostnamectl shim (writes /etc/hostname).

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[luisguzman-adfa]

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