Add branch lifecycle commands (branch, merge, archive) to the SDLC CLI.
Introduce orchestrator handler and service for multi-step SDLC workflows.
Expand skeleton template with 15 Claude commands covering the full feature
lifecycle. Extend classifier rules, error types, and executor port for
branch operations. Split rules.go and classifier_test.go to stay within
500-line limit.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
