feat: implement package and cli tool for repairing oidc links (#26418)

coderd/authlink/doc.go

@@ -0,0 +1,10 @@
+// Package authlink provides analysis and repair utilities for OIDC user link
+// records stored in the user_links table.
+//
+// When an OIDC provider is changed, the issuer (and possibly subject) in the
+// linked_id column changes. Because linked_id is composed as "issuer||subject",
+// existing users get locked out with "Account already linked" errors. The
+// functions in this package let an administrator inspect which links are
+// affected and reset the mismatched ones so users can re-authenticate under the
+// new provider.
+package authlink