feat(git-flow): add /gitflow setup with auto-config and CLAUDE.md injection

New gitflow-setup.md command auto-detects Gitea system config from
~/.config/claude/gitea.env, configures workflow settings, and injects
Git Workflow section into project CLAUDE.md. Moved
claude-md-integration.md to skills/ for programmatic use.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/git-flow/commands/gitflow-config.md

@@ -42,6 +42,7 @@ Configure git-flow settings interactively or display current configuration.
 5. Protected branches
 6. View all settings
 7. Reset to defaults
+8. Re-run setup wizard (redirects to `/gitflow setup`)
 
 ## Output