fix: keep reading initial_image, without documenting it

Systems in the field still carry the pre-2025-10 name, so app-init.sh reads it
again as a fallback. It stays out of the schema and out of the docs: one
documented key, not two spellings to choose between.

#include is written as an array everywhere in the docs.

Author: simonwalz

docs/common/cuos-app-init.md

@@ -32,7 +32,7 @@ Setting `init_image` yourself replaces it:
 
 ```json
 {
-  "#include": "cuos-release/release.json",
+  "#include": ["cuos-release/release.json"],
   "init_image": "your-registry/your-app",
   "init_image_version": "1.2.3",
   "init_image_digest": "sha256:..."

docs/quickstart.md

@@ -54,7 +54,7 @@ checkouts, which is where `output/` appears.
 Place it beside the two checkouts, as `system.json`.
 
 > Tip: For production pin versions & use digests — or
-> `"#include": "cuos-release/release.json"`, which pins them for you. It also
+> `"#include": ["cuos-release/release.json"]`, which pins them for you. It also
 > pins CuOS IaC as `init_image`, so leave that key out unless you bring your own
 > container — see
 > [Your Application Init Container](./common/cuos-app-init.md#cuos-iac-is-the-default-one).

system/cuos/app-init.sh

@@ -100,12 +100,15 @@ fi
 init_dialogs
 
 CONTAINER_NAME="cuos-app"
-if ! INITIAL_IMAGE="$(image_url "init")"; then
+# "initial_image" is the pre-2025-10 name and stays readable for systems in the
+# field that still carry it. It is deliberately absent from the schema and the
+# docs - not an alternative spelling to choose from.
+if ! INITIAL_IMAGE="$(image_url "init" || image_url "initial")"; then
   report_err "cuos:application:image_not_defined" "Application image not defined"
   action_on_failure
 fi
 INITIAL_IMAGE_VERSION="$(image_version "${INITIAL_IMAGE}")"
-INITIAL_DIGEST="$(jq -r '.init_image_digest // empty' "${CONFIG_PATH}")"
+INITIAL_DIGEST="$(jq -r '.init_image_digest // .initial_image_digest // empty' "${CONFIG_PATH}")"
 
 LAST_INITIAL_IMAGE="$(docker inspect --format='{{.Config.Image}}' "${CONTAINER_NAME}" 2>/dev/null)" || true
 LAST_INITIAL_IMAGE_VERSION="$(image_version "${LAST_INITIAL_IMAGE}")" || true