apply_config() now calls _load_registered_peers() when wg0.conf is empty
so all active peers from peers.json are written back into the config file
after a bootstrap — preventing clients from losing tunnel access after
an API restart that regenerated wg0.conf from scratch.
Adds test_wireguard_vpn_routing.py (36 tests) covering:
- generate_config() PostUp/PostDown rules enabling internet forwarding
(MASQUERADE + FORWARD ACCEPT required for internet-through-VPN)
- get_peer_config() DNS field pointing to cell-dns for domain resolution
- apply_config() bootstrap peer restoration from peers.json
- _load_registered_peers() filtering (inactive, missing fields, malformed)
- add_peer() /32 AllowedIPs enforcement to prevent route leaks
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
