artifact-rootfs: stop forcing SKIP_ARMBIAN_REPO=yes; default to no

With the new armbian-config-driven desktop install path running
inside rootfs-create.sh (module_desktops install mode="build"),
the rootfs-build chroot needs apt.armbian.com's <release>-utils
and <release>-desktop components reachable: armbian-config itself
lives in -utils, and firefox / chromium / gnome-branded packages
live in -desktop. Forcing SKIP_ARMBIAN_REPO=yes at artifact-rootfs
time meant create_sources_list_and_deploy_repo_key renamed
armbian.sources to armbian.sources.disabled before the desktop
install ran, so every apt install for those packages 404'd and
the rootfs cache shipped without them.

Drop the force. Default is now "no" (repo enabled, components
still intentionally exclude 'main' at this stage — see
distro-specific.sh:295 — so armbian/build's own .debs don't
collide). Boards / userpatches that specifically want the
repo-free rootfs behaviour can still set SKIP_ARMBIAN_REPO=yes
explicitly, and the existing downstream readers (rootfs-image.sh,
distro-specific.sh, bcm2711.conf, change-tracking.sh) honour it
unchanged.

Also fix the inverted documentation in config/boards/README.md:
it claimed SKIP_ARMBIAN_REPO=yes meant "Include (default)" and
no meant "Do NO include", which is the opposite of what the
variable name and all readers in the codebase actually do.

Author: igorpecovnik

config/boards/README.md

@@ -61,10 +61,10 @@ If you are unsure about the documentation then invoke `$ grep -r -A5 -B5 "BUILD_
 - **MODULES_BLACKLIST_EDGE** ( space-separated list of kernel modules ): appends modules to the kernel's blacklist/deny list for **edge** kernel
 - **SERIALCON** ( comma-separated list of terminal interfaces [:bandwidth] ): declares which serial console should be used on the system
 	- Example: `ttyS0:15000000,ttyGS1`
-- **SKIP_ARMBIAN_REPO** ( boolean ): Whether to include the armbian repository in the built image
+- **SKIP_ARMBIAN_REPO** ( boolean ): Whether to exclude the armbian repository from the built image
     - Values:
-        - yes: Include (default)
-        - no: Do NO include
+        - yes: Exclude the armbian repo (armbian.sources stays `.disabled`)
+        - no: Include the armbian repo (default)
 - **POWER_MANAGEMENT_FEATURES** (boolean): Controls whether system sleep functionality (suspend, hibernate, hybrid sleep) is allowed on the built image.
     - Values:
          - yes: Enable power-management sleep features (allow systemd sleep modes)

lib/functions/artifacts/artifact-rootfs.sh

@@ -151,9 +151,15 @@ function artifact_rootfs_cli_adapter_config_prep() {
 	declare -g -r RELEASE="${RELEASE}" # make readonly for finding who tries to change it
 	declare -g -r NEEDS_BINFMT="yes"   # make sure binfmts are installed during prepare_host_interactive
 
-	if [[ "${SKIP_ARMBIAN_REPO}" != "yes" ]]; then # if not set to yes, force it to yes.
-		declare -g SKIP_ARMBIAN_REPO="yes"            # Using the repo during rootfs build causes insanity, so don't. Make readonly to ensure.
-	fi
+	# Don't force SKIP_ARMBIAN_REPO=yes for rootfs artifact builds anymore.
+	# The new desktop install path (module_desktops install mode=build,
+	# invoked from rootfs-create.sh) needs apt.armbian.com's
+	# <release>-utils (armbian-config itself) and <release>-desktop
+	# (firefox, chromium, gnome-branded bits) components to be reachable
+	# while the rootfs is being assembled. Default to "no" (repo ON)
+	# and let boards/userpatches opt out explicitly if they still need
+	# the repo-free rootfs behaviour for whatever reason.
+	declare -g SKIP_ARMBIAN_REPO="${SKIP_ARMBIAN_REPO:-no}"
 	declare -g -r SKIP_ARMBIAN_REPO # make it readonly to ensure sanity if hooks try to change it
 
 	track_general_config_variables "in artifact_rootfs_cli_adapter_config_prep"