fix(#2417): hardcode external,gateway in forgejo webhook allowlist, drop option

nix/host-modules/hive-forge/default.nix

@@ -418,6 +418,18 @@ in
               # disallowed hosts"). Allow loopback + RFC-1918 sources
               # so an in-hive mirror of the hyperhive repo works.
               migrations.ALLOW_LOCALNETWORKS = true;
+              # `ALLOWED_HOST_LIST` is forgejo's webhook SSRF allow-list, and
+              # it's a STRICT whitelist (only listed hosts deliver). Its
+              # default is the `external` builtin: all public unicast IPs are
+              # allowed, private/loopback denied. We must KEEP `external` so
+              # user-repo webhooks to public hosts (github, slack, …) keep
+              # working, and ADD the hive gateway host on top: the config-PR +
+              # knowledge webhooks target `https://<hyperhive domain>/webhook/*`,
+              # which resolves to a private (RFC-1918) gateway IP that
+              # `external` alone would deny (so they'd only ever be caught by
+              # the 5-min poll fallback). Naming the single gateway host is
+              # tighter than the broad `private` builtin.
+              webhook.ALLOWED_HOST_LIST = "external,${hyperhiveDomain}";
               log.LEVEL = "Warn";
               ui = {
                 DEFAULT_THEME = "catppuccin-vibec0re";