When an agent registers using an IP address, check if any existing node's
hostname resolves to that same IP. This prevents duplicates when a node
was manually configured via hostname and later the agent is installed
which registers using the host's IP.
Changes:
- Add extractHostIP() to extract IP from URL if present
- Add resolveHostnameToIP() with 2s timeout for DNS resolution
- During agent auto-registration, check if existing hostname-based
configs resolve to the new IP and update instead of creating duplicates
- Add test for extractHostIP helper function
rcourtman
1dff90817f