chore(flake): treefmt + deadnix/statix + pre-commit; relocate work module

- treefmt-nix drives `nix fmt` and the formatting check (nixfmt/shfmt/
  prettier; generated files and flake.lock excluded). Replaces the
  bespoke find-based check.
- deadnix and statix as flake checks and pre-commit hooks; deadnix
  ignores module-arg patterns, statix.toml disables the two house-style
  lints (repeated_keys, empty_pattern). Fixed the one real deadnix hit
  (unused overlay arg) and statix hit (use inherit for claude-code).
- git-hooks.nix installs the pre-commit gate via the devShell.
- .editorconfig for the base style.
- Move system/modules/work/default.nix -> lyrathorpe/home/work.nix (it is
  a home-manager module). README gains a Development section; docs
  reformatted by the new formatter.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

flake.lock

@@ -40,6 +40,22 @@
       }
     },
     "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-compat_2": {
       "locked": {
         "lastModified": 1761640442,
         "narHash": "sha256-AtrEP6Jmdvrqiv4x2xa5mrtaIp3OEe8uBYCDZDS+hu8=",
@@ -54,7 +70,7 @@
         "type": "github"
       }
     },
-    "flake-compat_2": {
+    "flake-compat_3": {
       "flake": false,
       "locked": {
         "lastModified": 1767039857,
@@ -90,6 +106,49 @@
         "type": "github"
       }
     },
+    "git-hooks": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1778507602,
+        "narHash": "sha256-kTwur1wV+01SdqskVMSo6JMEpg71ps3HpbFY2GsflKs=",
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "rev": "61ab0e80d9c7ab14c256b5b453d8b3fb0189ba0a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "git-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"
+      }
+    },
     "home-manager": {
       "inputs": {
         "nixpkgs": [
@@ -172,7 +231,7 @@
     },
     "nixos-apple-silicon": {
       "inputs": {
-        "flake-compat": "flake-compat",
+        "flake-compat": "flake-compat_2",
         "nixpkgs": [
           "nixpkgs"
         ]
@@ -193,7 +252,7 @@
     },
     "nixos-wsl": {
       "inputs": {
-        "flake-compat": "flake-compat_2",
+        "flake-compat": "flake-compat_3",
         "nixpkgs": [
           "nixpkgs"
         ]
@@ -248,6 +307,7 @@
       "inputs": {
         "firefox-addons": "firefox-addons",
         "flake-parts": "flake-parts",
+        "git-hooks": "git-hooks",
         "home-manager": "home-manager",
         "nix-darwin": "nix-darwin",
         "nix-homebrew": "nix-homebrew",
@@ -255,7 +315,28 @@
         "nixos-apple-silicon": "nixos-apple-silicon",
         "nixos-wsl": "nixos-wsl",
         "nixpkgs": "nixpkgs",
-        "nixpkgs-unstable": "nixpkgs-unstable"
+        "nixpkgs-unstable": "nixpkgs-unstable",
+        "treefmt-nix": "treefmt-nix"
+      }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1780220602,
+        "narHash": "sha256-eynAfOmbmxJnkp7YewvCEbShNnnYJ9gLLqkzsYtBPeM=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "db947814a175b7ca6ded66e21383d938df01c227",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
       }
     }
   },