fix: Make Nix flake compatible with macOS

- Make inotify-tools Linux-only (not available on Darwin)
- Replace nixfmt-rfc-style with nixfmt (deprecated warning)
- Add flake.lock for reproducible builds

Changes:
- nix/shell.nix: Conditionally include inotify-tools only on Linux
- flake.nix: Use pkgs.nixfmt instead of pkgs.nixfmt-rfc-style
- flake.lock: Lock dependencies for reproducibility

flake.lock

@@ -0,0 +1,124 @@
+{
+  "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1767039857,
+        "narHash": "sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns=",
+        "owner": "NixOS",
+        "repo": "flake-compat",
+        "rev": "5edf11c44bc78a0d334f6334cdaf7d60d732daab",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1769996383,
+        "narHash": "sha256-AnYjnFWgS49RlqX7LrC4uA+sCCDBj0Ry/WOJ5XWAsa0=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "57928607ea566b5db3ad13af0e57e921e6b12381",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "pre-commit-hooks",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709087332,
+        "narHash": "sha256-HG2cCnktfHsKV0s4XW83gU3F57gaTljL9KNSuG6bnQs=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1770197578,
+        "narHash": "sha256-AYqlWrX09+HvGs8zM6ebZ1pwUqjkfpnv8mewYwAo+iM=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "00c21e4c93d963c50d4c0c89bfa84ed6e0694df2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1769939035,
+        "narHash": "sha256-Fok2AmefgVA0+eprw2NDwqKkPGEI5wvR+twiZagBvrg=",
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "a8ca480175326551d6c4121498316261cbb5b260",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-parts": "flake-parts",
+        "nixpkgs": "nixpkgs",
+        "pre-commit-hooks": "pre-commit-hooks",
+        "systems": "systems"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -53,7 +53,7 @@
         };
 
         # Nix formatter for flake files
-        formatter = pkgs.nixfmt-rfc-style;
+        formatter = pkgs.nixfmt;
       };
 
       flake = {

nix/shell.nix

@@ -15,10 +15,9 @@
   pkg-config,
   # Development tools
   git-lfs,
-  inotify-tools,
   # LSPs and formatters
   elixir-ls,
-  nixfmt-rfc-style,
+  nixfmt,
   shellcheck,
   # Pre-commit hooks
   pre-commit-hooks,
@@ -182,7 +181,7 @@ let
       # Nix formatting
       nixfmt = {
         enable = true;
-        entry = "${nixfmt-rfc-style}/bin/nixfmt";
+        entry = "${nixfmt}/bin/nixfmt";
       };
 
       # Shellcheck for shell scripts
@@ -213,16 +212,18 @@ mkShell {
 
     # Development tools
     git-lfs
-    inotify-tools # For Mix file watching
 
     # LSPs and formatters
     elixir-ls
-    nixfmt-rfc-style
+    nixfmt
     shellcheck
 
     # Service management scripts
     startServices
     stopServices
+  ] ++ lib.optionals lib.isLinux [
+    # Linux-only tools
+    inotify-tools # For Mix file watching
   ];
 
   # Environment variables