flake: update nixos-exporter and set configurationRevision

- Update nixos-exporter to 0.2.3
- Set system.configurationRevision for all hosts so the exporter
  can report the flake's git revision

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.lock

@@ -49,11 +49,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1770422123,
+        "lastModified": 1770422522,
-        "narHash": "sha256-kh0CJu1wVCSCWBuW00i6Ooh3jGFxKdtUtIBAb2sY8LI=",
+        "narHash": "sha256-WmIFnquu4u58v8S2bOVWmknRwHn4x88CRfBFTzJ1inQ=",
         "ref": "refs/heads/master",
-        "rev": "04eba77ac028033b6dfed604eb1b5664b46acc77",
+        "rev": "cf0ce858997af4d8dcc2ce10393ff393e17fc911",
-        "revCount": 10,
+        "revCount": 11,
         "type": "git",
         "url": "https://git.t-juice.club/torjus/nixos-exporter"
       },

flake.nix

@@ -53,6 +53,7 @@
           { config, pkgs, ... }:
           {
             nixpkgs.overlays = commonOverlays;
+            system.configurationRevision = self.rev or self.dirtyRev or "dirty";
           }
         )
         sops-nix.nixosModules.sops