Setup Devcontainer

Generates .devcontainer/ from the templates in templates/: a baseline Claude Code devcontainer setup with repo-specific values replaced by placeholders. One always-written baseline, plus two independent opt-ins:

• baseline — Claude Code + gh CLI + persistent auth + skill sync. Always written.
• SSH layer — deploy-key/signing-key automation for agent-driven git push and signed commits. Optional, and addable after the fact without touching the baseline files.
• YOLO alias — a claude-yolo shell alias (claude --dangerously-skip-permissions --worktree --remote-control) for fast, unattended iteration. Optional — some developers don't want a no-holds-barred agent available inside the container at all.

1. Detect the target repo

git remote get-url origin