🔧 Complete Docker template update runbook 🔧

Finish syncing generated Docker template files against upstream templates:
remove dead template-files ARGs from the Dockerfile, sync bin-script
boilerplate to the current shell/sh template, migrate the non-standard
rootfs/etc dir to rootfs/tmp/etc, fix a gitignore bug that silently dropped
rootfs/tmp/, correct the README license, and document the go-tools
toolchain-stage exception in the runbook.
- AI.md: document that language toolchain build stages (e.g. `FROM golang:alpine AS go-tools`)
are intentionally exempt from the PULL_URL/GEN_DOCKERFILE_APP_DIR org rule
- Dockerfile: remove dead DEFAULT_FILE_DIR/DEFAULT_DATA_DIR/DEFAULT_CONF_DIR/DEFAULT_TEMPLATE_DIR
ARGs and their mkdir usage — the template-files directory no longer exists
- README.md: fix stale license claim (MIT) to match the actual LICENSE.md (WTFPL)
- .gitignore: anchor the tmp/ pattern to /tmp/ so it stops silently swallowing
the required rootfs/tmp/ directory
- rootfs/etc/profile.d/go.sh -> rootfs/tmp/etc/profile.d/go.sh: migrate the
non-standard rootfs/etc dir to the tmp/etc convention (rootfs/root, rootfs/tmp,
rootfs/usr are the only valid rootfs root dirs; 03-files.sh copies tmp/etc/* at build time)
- rootfs/usr/local/bin/copy, rootfs/usr/local/bin/symlink: sync APPNAME
assignment to the current template style and add the missing trap '' EXIT line
- rootfs/usr/local/bin/healthcheck: sync APPNAME assignment and add the
missing trap '' EXIT line

AI.md
Dockerfile
.gitignore
README.md
rootfs/etc/profile.d/go.sh
rootfs/tmp/
rootfs/usr/local/bin/copy
rootfs/usr/local/bin/healthcheck
rootfs/usr/local/bin/symlink

rootfs/usr/local/bin/symlink

@@ -20,7 +20,7 @@
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # shellcheck disable=SC1001,SC1003,SC2001,SC2003,SC2016,SC2031,SC2090,SC2115,SC2120,SC2155,SC2199,SC2229,SC2317,SC2329
 # - - - - - - - - - - - - - - - - - - - - - - - - -
-APPNAME="$(basename -- "$0" 2>/dev/null)"
+APPNAME="${0##*/}"
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # colorization
 if [ -n "$NO_COLOR" ]; then
@@ -56,6 +56,8 @@ __ln_sf() {
 DEFAULT_COLOR="254"
 SYMLINK_EXIT_STATUS=0
 # - - - - - - - - - - - - - - - - - - - - - - - - -
+trap '' EXIT
+# - - - - - - - - - - - - - - - - - - - - - - - - -
 # Main application
 if [ $# -ne 2 ]; then
   __printf_color "USAGE: $APPNAME from to" "2" >&2