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/Dockerfile

@@ -1,10 +1,9 @@
-ARG BUILD_FROM=ghcr.io/hassio-addons/base:latest
 FROM technitium/dns-server:latest
 
 ENV DNS_SERVER_WEB_SERVICE_HTTPS_PORT=53443 \
     DNS_SERVER_WEB_SERVICE_ENABLE_HTTPS=false
 
-COPY entrypoint.sh /entrypoint.sh
-RUN chmod +x /entrypoint.sh
-
-ENTRYPOINT ["/entrypoint.sh"]
+# Technitium hardcodes /etc/dns as its config dir. HA's addon_config mounts
+# at /config (persistent). Replace the real dir with a symlink so Technitium
+# writes through to the persistent volume.
+RUN rm -rf /etc/dns && mkdir -p /config/dns && ln -s /config/dns /etc/dns