* feat: support allocating public IPv6 addresses from a provider
Add a provider/leaser architecture for public IPv6 address allocation
between nodes in the same network:
- A node with `--ipv6-public-addr-provider` advertises a delegable
public IPv6 prefix (auto-detected from kernel routes or manually
configured via `--ipv6-public-addr-prefix`).
- Other nodes with `--ipv6-public-addr-auto` request a /128 lease from
the selected provider via a new RPC service (PublicIpv6AddrRpc).
- Leases have a 30s TTL, renewed every 10s by the client routine.
- The provider allocates addresses deterministically from its prefix
using instance-UUID-based hashing to prefer stable assignments.
- Routes to peer leases are installed on the TUN device, and each
client's own /128 is assigned as its IPv6 address.
Also includes netlink IPv6 route table inspection, integration tests,
and event-driven route/address reconciliation.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
KKRainbow