[sh1pt-actions-fleet]

What changed

• Resolve Forward Email's generated DKIM selector through its authenticated domain API.
• Confirm Forward Email reports DNS verified and the selector's TXT record is publicly present before reporting DKIM pass.
• Keep the current warning when API verification is unavailable or the published key is missing.
• Add the API token to the OutreachGraph production vault.

Verification

• Mailbox DNS tests pass.
• Provider, pipeline, and API typechecks pass.
• Live check for profullstack.com reports DKIM pass with selector fe-36190d4cf0._domainkey.