Implement checkPing (pro-bing ICMP), checkPort (TCP dial), and checkDNS
(miekg/dns) with per-monitor timeout, configurable DNS record types,
and fallback defaults. Groups skip checks entirely.
Add Hostname, Port, Timeout, Method, Description, ParentID, AcceptedCodes,
DNSResolveType, DNSServer, and IgnoreTLS fields. Refactor AddSite/UpdateSite
to accept models.Site instead of individual params. Includes DB migrations
for existing databases, per-monitor timeout/TLS in the engine, new type
options in TUI forms, and TYPE column in the sites table.
lerko