HEDNS: support init command

[TomOnTime]

Summary

Register CredsMetadata for HEDNS so the provider is offered by the dnscontrol init wizard.

Fields mirror the entries in integrationTest/profiles.json.

CC: @rblenkinsopp

Test plan

• go build ./... passes
• dnscontrol init lists HEDNS as an option
• Verify any // TODO: Verify annotations in the diff (e.g. PortalURL)

🤖 Generated with Claude Code

[rblenkinsopp]

Yes, this is the correct URL, I'm not sure why this is TODO as this is very easy to verify, was this Claude submission actually reviewed?

[rblenkinsopp]

I would change this (as the account is broader than just DNS):

Suggested change

	Help: "Your dns.he.net account username.",
	Help: "Your Hurricane Electric account username.",

[rblenkinsopp]

Suggested change

	Help: "Your dns.he.net account password.",
	Help: "Your Hurricane Electric account password.",

[rblenkinsopp]

For this, I'd be inclined to set the default to ., as without this the user will get the suprising behaviour only being able to issue one command every 30 seconds if TOTP is enabled.

Suggested change

	{
	Key: "session-file-path",
	Label: "Session file path (optional)",
	Help: "Path to a directory where the .hedns-session file is stored to reuse the authenticated session. Leave blank to log in each run.",
	},
	{
	Key: "session-file-path",
	Label: "Session file path (optional)",
	Help: "Path to a directory where the .hedns-session file is stored to reuse the authenticated session. Leave blank to log in each run.",
	Default: ".",
	},

While this is slightly less secure, it is documented in the associated documentation, and since this is for the init getting started workflow, I would favour useability in this instance.

[rblenkinsopp]

Thanks for the submission, mostly looks good with a some minor suggestions/alterations.