update nixpkgs

bitcoin: 30.0 -> 30.2
bitcoind: 30.0 -> 30.2
bitcoind-knots: 29.2.knots20251110 -> 29.3.knots20260210
btcpayserver: 2.2.1 -> 2.3.4
clightning: 25.09.2 -> 25.12.1
elementsd: 23.2.4 -> 23.3.2
lnd: 0.19.3-beta -> 0.20.1-beta

lnd 0.20 makes its chain notifier subsystem ready later in startup
than its RPC server. lightning-loop and lightning-pool both subscribe
to chain notifications right after dialing lnd, which fails before
the notifier is up and crashes the daemon. Add a 5s ExecStartPre
sleep to both services as a temporary workaround.

modules/lightning-loop.nix

@@ -128,6 +128,8 @@ in {
       requires = [ "lnd.service" ];
       after = [ "lnd.service" "nix-bitcoin-secrets.target" ];
       serviceConfig = nbLib.defaultHardening // {
+        # TODO: temporary sleep to prevent race condition
+        ExecStartPre = "${pkgs.coreutils}/bin/sleep 5";
         ExecStart = "${cfg.package}/bin/loopd --configfile=${configFile}";
         User = lnd.user;
         Restart = "on-failure";