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.

flake.lock

@@ -44,11 +44,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1767480499,
-        "narHash": "sha256-8IQQUorUGiSmFaPnLSo2+T+rjHtiNWc+OAzeHck7N48=",
+        "lastModified": 1772822230,
+        "narHash": "sha256-yf3iYLGbGVlIthlQIk5/4/EQDZNNEmuqKZkQssMljuw=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "30a3c519afcf3f99e2c6df3b359aec5692054d92",
+        "rev": "71caefce12ba78d84fe618cf61644dce01cf3a96",
         "type": "github"
       },
       "original": {
@@ -60,11 +60,11 @@
     },
     "nixpkgs-25_05": {
       "locked": {
-        "lastModified": 1767051569,
-        "narHash": "sha256-0MnuWoN+n1UYaGBIpqpPs9I9ZHW4kynits4mrnh1Pk4=",
+        "lastModified": 1767313136,
+        "narHash": "sha256-16KkgfdYqjaeRGBaYsNrhPRRENs0qzkQVUooNHtoy2w=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "40ee5e1944bebdd128f9fbada44faefddfde29bd",
+        "rev": "ac62194c3917d5f474c1a844b6fd6da2db95077d",
         "type": "github"
       },
       "original": {
@@ -76,11 +76,11 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1767364772,
-        "narHash": "sha256-fFUnEYMla8b7UKjijLnMe+oVFOz6HjijGGNS1l7dYaQ=",
+        "lastModified": 1772736753,
+        "narHash": "sha256-au/m3+EuBLoSzWUCb64a/MZq6QUtOV8oC0D9tY2scPQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "16c7794d0a28b5a37904d55bcca36003b9109aaa",
+        "rev": "917fec990948658ef1ccd07cef2a1ef060786846",
         "type": "github"
       },
       "original": {