fix: health history all-down — connectivity checks and UI data path

Service manager fixes (connectivity tests):
- email_manager: replace telnet with socket.create_connection for SMTP/IMAP;
  replace nslookup with socket.getaddrinfo for DNS; exclude unconfigured domain
  from success (email healthy=False now correctly means ports refused, not missing domain)
- calendar_manager: replace localhost:5232 with cell-radicale:5232;
  fix database check to test dir writability instead of file existence (files created on demand)
- file_manager: replace localhost:8080 with cell-webdav:80; add top-level success key
- network_manager: replace nslookup with socket.getaddrinfo;
  add success key to dhcp_test and ntp_test return values
- routing_manager: exclude iptables_access from success
  (iptables runs in cell-wireguard, not API container)
- wireguard_manager: add success key to no-arg test_connectivity result

Health history UI:
- SvcCol reads data?.status?.running || data?.status?.status — handles nested health check shape

Result: network/wireguard/calendar/files/routing/vault all healthy=True.
Email healthy=False is correct — mail server needs ≥1 account before Dovecot starts.

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

api/wireguard_manager.py

@@ -515,7 +515,8 @@ class WireGuardManager(BaseServiceManager):
         """Ping a peer IP and return results. Called with no args from health_check."""
         if not peer_ip:
             status = self.get_status()
-            return {'reachable': status.get('running', False), 'status': status.get('status')}
+            running = status.get('running', False)
+            return {'success': running, 'reachable': running, 'status': status.get('status')}
         try:
             result = subprocess.run(
                 ['ping', '-c', '1', '-W', '2', peer_ip],