fix: correct DNS records, peer dashboard field names, and services API response

- network_manager: api/webui DNS records now point to Caddy (172.20.0.2)
  instead of their container IPs so Caddy can reverse-proxy correctly
- ip_utils: add webui.dev block to generated Caddyfile
- config/caddy/Caddyfile: regenerated with webui.dev block
- config/dns/Corefile: simplify to single forward zone (remove duplicate)
- app.py peer_dashboard: rename peer_name→name, rx_bytes→transfer_rx,
  tx_bytes→transfer_tx to match PeerDashboard.jsx; add service_urls dict
- app.py peer_services: fix DNS (10.0.0.1→real CoreDNS IP), CalDAV URL
  (radicale.dev:5232→calendar.dev), email structure (flat→nested smtp/imap
  objects), rename webdav→files, add WireGuard config text, add username field
- PeerDashboard.jsx: render service icon links from service_urls

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/network_manager.py

@@ -150,13 +150,21 @@ class NetworkManager(BaseServiceManager):
         return {'restarted': restarted, 'warnings': warnings}
 
     def _build_dns_records(self, cell_name: str, ip_range: str) -> List[Dict]:
-        """Build the standard set of DNS A records for the given subnet."""
+        """Build the standard set of DNS A records for the given subnet.
+
+        All user-facing names resolve to the Caddy reverse proxy (caddy IP) so
+        the Host header is passed through and Caddy routes based on it.
+        Exception: calendar/files/mail/webdav use dedicated virtual IPs so that
+        iptables per-service firewall rules can target them by destination IP.
+        api and webui also go through Caddy — they don't have their own VIPs and
+        their containers don't serve HTTP on port 80.
+        """
         import ip_utils
         ips = ip_utils.get_service_ips(ip_range)
         return [
             {'name': cell_name,  'type': 'A', 'value': ips['caddy']},
-            {'name': 'api',      'type': 'A', 'value': ips['api']},
-            {'name': 'webui',    'type': 'A', 'value': ips['webui']},
+            {'name': 'api',      'type': 'A', 'value': ips['caddy']},
+            {'name': 'webui',    'type': 'A', 'value': ips['caddy']},
             {'name': 'calendar', 'type': 'A', 'value': ips['vip_calendar']},
             {'name': 'files',    'type': 'A', 'value': ips['vip_files']},
             {'name': 'mail',     'type': 'A', 'value': ips['vip_mail']},