feat(nixos): add Bambu Studio Flatpak

Manage the user Flatpak through nix-flatpak and enable printer discovery through the host firewall.

flake.lock

@@ -321,6 +321,22 @@
         "type": "github"
       }
     },
+    "nix-flatpak": {
+      "locked": {
+        "lastModified": 1767983141,
+        "narHash": "sha256-7ZCulYUD9RmJIDULTRkGLSW1faMpDlPKcbWJLYHoXcs=",
+        "owner": "gmodena",
+        "repo": "nix-flatpak",
+        "rev": "440818969ac2cbd77bfe025e884d0aa528991374",
+        "type": "github"
+      },
+      "original": {
+        "owner": "gmodena",
+        "ref": "v0.7.0",
+        "repo": "nix-flatpak",
+        "type": "github"
+      }
+    },
     "nixos-hardware": {
       "inputs": {
         "nixpkgs": [
@@ -456,6 +472,7 @@
         "firefox-addons": "firefox-addons",
         "gitea-axi": "gitea-axi",
         "home-manager": "home-manager_3",
+        "nix-flatpak": "nix-flatpak",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs_2",
         "nixpkgs-stable": "nixpkgs-stable",