Reword the wrong site password message

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/gate.go

@@ -118,7 +118,7 @@ func (s *Server) handleUnlock(w http.ResponseWriter, r *http.Request) {
 	}
 	if !auth.CheckPassword(hash, password) {
 		s.loginLimit.Fail("unlock:" + ip)
-		page.Error = "That's not the password."
+		page.Error = "Password incorrect."
 		s.render(w, r, http.StatusUnauthorized, "gate", "", page)
 		return
 	}