feat(nix): add sops for secrets

flake.lock

@@ -344,7 +344,8 @@
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs_2",
         "nixpkgs-quartus": "nixpkgs-quartus",
-        "nixpkgs-xr": "nixpkgs-xr"
+        "nixpkgs-xr": "nixpkgs-xr",
+        "sops-nix": "sops-nix"
       }
     },
     "rust-overlay": {
@@ -368,6 +369,26 @@
         "type": "github"
       }
     },
+    "sops-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1760998189,
+        "narHash": "sha256-ee2e1/AeGL5X8oy/HXsZQvZnae6XfEVdstGopKucYLY=",
+        "owner": "Mic92",
+        "repo": "sops-nix",
+        "rev": "5a7d18b5c55642df5c432aadb757140edfeb70b3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "Mic92",
+        "repo": "sops-nix",
+        "type": "github"
+      }
+    },
     "systems": {
       "locked": {
         "lastModified": 1689347949,