fix: symlink /etc/dns to /config/dns at build time, drop entrypoint

rm -rf the real /etc/dns dir before symlinking so it replaces rather
than nests. Technitium now writes directly to the persistent
addon_config mount — no entrypoint shim needed.

technitium_dns/entrypoint.sh

@@ -1,22 +0,0 @@
-#!/bin/sh
-set -e
-
-# Technitium ships /etc/dns as a real directory in the image. We need it
-# to point at the persistent HA add-on config volume instead. Remove the
-# directory and replace with a symlink at runtime (after HA mounts volumes).
-
-DATA="/config/dns"
-
-mkdir -p "$DATA"
-
-if [ -d /etc/dns ] && [ ! -L /etc/dns ]; then
-    # Seed: copy any existing default config into the volume on first run
-    if [ -z "$(ls -A "$DATA" 2>/dev/null)" ]; then
-        cp -a /etc/dns/. "$DATA"/
-    fi
-    rm -rf /etc/dns
-fi
-
-ln -sf "$DATA" /etc/dns
-
-exec dotnet DnsServerApp.dll