home: add claude-code program with home-manager module

Configures claude-code using the home-manager programs.claude-code module:
- Settings: model, gopls plugin, auto-update disabled, permissions
- Agents: docs-verifier, security-reviewer
- Skills: pr summary generator

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

home/packages/default.nix

@@ -13,7 +13,6 @@ in
     bat
     bzip2
     chromium
-    claude-code-bin
     croc
     devenv
     distrobox