tailscaled does not reliably enable IPv6 forwarding inside a container
network namespace ('IPv6 forwarding is disabled'), so advertised IPv6
subnet routes silently fail. Add a tiny entrypoint.sh that sets
net.ipv4.ip_forward and net.ipv6.conf.all.forwarding (writable inside a
RouterOS container netns), then exec's tailscaled. Built in the builder
stage so it stays in the single /usr/local/bin COPY layer.
Verified: privileged run flips v6 forwarding 0->1 and exec's tailscaled
with CMD args intact.
README shrinks to a repo intro with pointers. Separate the three
audiences:
- docs/USAGE.md deploy the prebuilt image on RouterOS + operate it
- docs/DEVELOPMENT.md build, local test, version bump, cut releases
- docs/DESIGN.md size optimizations, feature allowlist, why the
updater and netmap disk-cache are removed, flash-wear
protection, versioning/release architecture, the
overlayfs layer-duplication gotcha, dependency pinning