docker: install from the docker-ce repo on RHEL-family hosts

bootstrap failed outright on Oracle Linux: docker/install.sh piped
get.docker.com to sh, and that script allowlists distros by /etc/os-release
ID, so it aborted with "ERROR: Unsupported distribution 'ol'".

On a distro it does recognize, the convenience script only adds the repo and
installs the packages -- exactly what install_rhel() now does directly. Doing
it ourselves drops the allowlist, so every EL rebuild (Oracle, Rocky, Alma,
CentOS, RHEL) goes through one code path instead of needing to be enumerated.
Debian-family still uses get.docker.com. containerd.io needs --allowerasing to
replace the runc that Oracle Linux ships.

Also stop one failed module from killing the whole run: modules were bare
calls under `set -eu`, so docker/'s exit meant bin/, node/ and ansible/
silently never ran -- an unsupported distro string left the box with no CLIs,
no npx and no ansible. run_module warns and continues, then bootstrap exits
non-zero with a summary of what failed. Same guard 35befbe added for
individual tools in bin/install.sh, one level up.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -32,8 +32,11 @@ Already have a clone? Just run it directly:
 - `git/` — sets git `user.name`/`user.email` and configures
   `credential.helper store` (plaintext `~/.git-credentials`, 0600) for
   HTTPS auth.
-- `docker/` — installs full (rootful) Docker Engine via get.docker.com,
-  enables the service (systemd hosts), and adds the invoking user to the
+- `docker/` — installs full (rootful) Docker Engine from Docker's upstream
+  package repo (get.docker.com on Debian-family; the docker-ce repo wired up
+  directly on RHEL-family, since the convenience script rejects EL rebuilds
+  like Oracle Linux by name), enables the service (systemd hosts), and adds
+  the invoking user to the
   `docker` group (takes effect at next login). No-ops where a rootless
   Docker daemon is already running (e.g. Kasm) so it never fights that
   setup. Uses sudo.