Initial commit: Chrony NTP Server add-on for Home Assistant

- NTP client syncs from configurable pools and servers
- NTP server mode serves time to LAN clients
- Web UI dashboard showing sync status, sources, and clients
- Supports iburst and maxsources options

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chrony-addon/Dockerfile

@@ -0,0 +1,18 @@
+ARG BUILD_FROM
+FROM $BUILD_FROM
+
+# Install chrony, jq for config parsing, and python for status dashboard
+RUN apk add --no-cache \
+    chrony \
+    jq \
+    python3 \
+    py3-flask
+
+# Copy root filesystem
+COPY rootfs /
+
+# Make scripts executable
+RUN chmod a+x /etc/s6-overlay/s6-rc.d/chrony/run \
+    && chmod a+x /etc/s6-overlay/s6-rc.d/webui/run
+
+WORKDIR /