feat: Add deploy-rs integration with basic configuration

- Add deploy-rs as flake input
- Configure deploy.nodes for all 4 machines (sleeper-service, grey-area, reverse-proxy, congenital-optimist)
- Include safety features: autoRollback, magicRollback, activation timeouts
- Add deploy-rs checks for validation
- Successfully tested dry-run deployment

This completes Tasks 1-3 from the deploy-rs integration roadmap.

flake.lock

@@ -1,17 +1,53 @@
 {
   "nodes": {
+    "deploy-rs": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "nixpkgs": "nixpkgs",
+        "utils": "utils"
+      },
+      "locked": {
+        "lastModified": 1749105467,
+        "narHash": "sha256-hXh76y/wDl15almBcqvjryB50B0BaiXJKk20f314RoE=",
+        "owner": "serokell",
+        "repo": "deploy-rs",
+        "rev": "6bc76b872374845ba9d645a2f012b764fecd765f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "serokell",
+        "repo": "deploy-rs",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1733328505,
+        "narHash": "sha256-NeCCThCEP3eCl2l/+27kNNK7QrwZB1IJCrXfrbv5oqU=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "ff81ac966bb2cae68946d5ed5fc4994f96d0ffec",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1749024892,
-        "narHash": "sha256-OGcDEz60TXQC+gVz5sdtgGJdKVYr6rwdzQKuZAJQpCA=",
+        "lastModified": 1743014863,
+        "narHash": "sha256-jAIUqsiN2r3hCuHji80U7NNEafpIMBXiwKlSrjWMlpg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8f1b52b04f2cb6e5ead50bd28d76528a2f0380ef",
+        "rev": "bd3bac8bfb542dbde7ffffb6987a1a1f9d41699f",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-25.05",
+        "ref": "nixpkgs-unstable",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -32,11 +68,61 @@
         "type": "github"
       }
     },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1749024892,
+        "narHash": "sha256-OGcDEz60TXQC+gVz5sdtgGJdKVYr6rwdzQKuZAJQpCA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "8f1b52b04f2cb6e5ead50bd28d76528a2f0380ef",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
-        "nixpkgs": "nixpkgs",
+        "deploy-rs": "deploy-rs",
+        "nixpkgs": "nixpkgs_2",
         "nixpkgs-unstable": "nixpkgs-unstable"
       }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
+    "utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
     }
   },
   "root": "root",