swarm-ui link-account forms: keep the sent name, drop secrets, one word for forge

The success line of both link forms read the live text field, so editing
the name after a link changed the sentence. The result now carries the
name that was sent.

The matrix form held the typed token and password after a failed submit,
and kept them across a switch of credential mode. It now drops them when
the request ends and when the mode changes.

The linked-accounts list and the delete dialog said forgejo where the
link menu and forms say forge; they now say forge.

frontend/packages/swarm-ui/src/agent/detail/account-kind.ts

@@ -0,0 +1,6 @@
+// What the operator calls an account kind. The wire value for a forge
+// account is "forgejo", but the link menu and form say "forge", so the list
+// and the delete dialog say it too.
+export function accountKindLabel(kind: string): string {
+  return kind === "forgejo" ? "forge" : kind;
+}