feat(claude): disable commit signature and fix permission syntax

- Add includeCoAuthoredBy option set to false
- Update customInstructions to exclude signature from commits
- Fix Bash permission syntax from "git *" to "git:*"

home.nix

@@ -166,6 +166,23 @@
   # Use kickstart.nvim configuration from flake
   programs.neovim-kickstart.enable = true;
 
+  # Claude Code configuration
+  home.file.".claude/settings.json" = {
+    text = builtins.toJSON {
+      permissions = {
+        allow = [
+          "Edit"
+          "Write"
+          "Bash(git:*)"
+        ];
+      };
+      customInstructions = "When working in a git repository, always use conventional commits format (e.g., feat:, fix:, docs:, style:, refactor:, test:, chore:) for commit messages. Do not include the Claude Code signature or Co-Authored-By line in commit messages.";
+      alwaysThinkingEnabled = true;
+      includeCoAuthoredBy = false;
+    };
+    force = true;
+  };
+
   programs.ssh = {
     enable = true;
     enableDefaultConfig = false;