feat: add dnsmasq DNS record admin UI

- store records in SQLite via built-in node:sqlite, no native deps
- wrap DB reads in await io() so they stay out of the static shell
- add CRUD pages backed by Server Actions with per-request data
- generate managed config and restart container via Docker socket
- add /resolve page to query dnsmasq for A and CNAME records
- add Dockerfile and compose setup with shared config volume

.env.example

@@ -0,0 +1,19 @@
+# Copy to .env.local and adjust for your setup. Every value is optional — the app falls back
+# to local paths under ./data so it runs with no configuration at all.
+
+# SQLite database — the single source of truth for records. Docker: /data/dnsmasq-admin.db
+DNSMASQ_ADMIN_DB_PATH=./data/dnsmasq-admin.db
+
+# Managed dnsmasq config file this app regenerates on every apply.
+# Docker: /etc/dnsmasq.d/dnsmasq-admin.conf
+DNSMASQ_ADMIN_CONF_PATH=./data/dnsmasq-admin.conf
+
+# Container restarted over the Docker socket after an apply.
+DNSMASQ_CONTAINER_NAME=dnsmasq
+
+# Docker socket. If it is missing (e.g. developing on Windows), the restart is skipped and
+# reported in the UI rather than failing.
+DNSMASQ_ADMIN_DOCKER_SOCKET=/var/run/docker.sock
+
+# DNS server used by the /resolve page. Point this at your dnsmasq container or LAN IP.
+DNSMASQ_SERVER_IP=127.0.0.1