🔧 Fix blueonyx build scripts and add CLAUDE.md + PLAN.md 🔧

Fix two build-breaking issues in setup scripts and update BUILD_DATE.
Add repo documentation files.
- Dockerfile: update BUILD_DATE from 202509161146 to 202605131434
- rootfs/root/docker/setup/02-packages.sh: remove broken reboot and sudo dnf commands that abort Docker build; BlueOnyx installation is done in 05-custom.sh
- rootfs/root/docker/setup/03-files.sh: remove irrelevant incus binary download from GitHub (fails in buildx sandbox; unrelated to BlueOnyx)
- CLAUDE.md: new file documenting systemd-container architecture, build notes, runtime requirements, and env vars
- PLAN.md: new file documenting migration steps, build command, smoke test procedure

CLAUDE.md
Dockerfile
PLAN.md
rootfs/root/docker/setup/02-packages.sh
rootfs/root/docker/setup/03-files.sh

Dockerfile

@@ -1,7 +1,7 @@
 # Docker image for blueonyx using the rhel template
 ARG IMAGE_NAME="blueonyx"
 ARG PHP_SERVER="blueonyx"
-ARG BUILD_DATE="202509161146"
+ARG BUILD_DATE="202605131434"
 ARG LANGUAGE="en_US.UTF-8"
 ARG TIMEZONE="America/New_York"
 ARG WWW_ROOT_DIR="/usr/local/share/httpd/default"