- Add explicit dynamic prefix keyword for NDP proxy:
- `service ndp-proxy interface <wan-if> prefix dynamic ...`
- Rendering behavior for dynamic NDP rules:
- `dynamic` -> `rule ::/0` (handled by `ndppd` with selected mode)
- Add RA base interface support for WAN SLAAC -> LAN RA prefix derivation:
- `service router-advert interface <lan-if> prefix ::/64 base-interface <wan-if>`
- Renders `Base6Interface <wan-if>;` in `radvd.conf`
- Refactor/fix NDP proxy verification:
- Fix `rule/prefix` key mismatch bug in `service_ndp-proxy.py`
- Enforce `dynamic` cannot use `mode static` (must be `auto` or `interface`)
- Add RA validation guard:
- `base-interface` is only allowed with wildcard `::/64` prefix
- Extend smoketests:
- global NDP dynamic prefix positive/negative cases
- router-advert `base-interface` positive/negative cases