fix: change module path to github.com/dolonet/mtg-multi
go install github.com/dolonet/mtg-multi@latest was broken because go.mod
declared module path as github.com/9seconds/mtg/v2 while the repo lives
at github.com/dolonet/mtg-multi. Users ended up installing upstream
binary without multi-secret support.
Fixes https://github.com/9seconds/mtg/issues/376#issuecomment-4162877568
Support multiple named secrets in [secrets] config section. During
FakeTLS handshake each secret is tried until HMAC validates. Matched
secret name is logged and used for per-user statistics tracking.
Built-in HTTP stats API (configurable via api-bind-to) exposes
GET /stats with per-user connection counts, bytes in/out, and
last-seen timestamps.
Backward compatible: single "secret" config key still works.
Add public-ipv4/public-ipv6 config options for manual IP override
On some servers ifconfig.co is unreachable (e.g. Hetzner, AdGuard DNS
blocklists), causing 'mtg doctor' SNI-DNS check and 'mtg access' link
generation to fail. New config options allow specifying public IPs
manually, with automatic detection as fallback.
Fixes #405