feat: add homebrew tap support, memory expansion, prompts

- Add SIGTERM handler for clean launchd shutdown
- Add --version flag for homebrew formula test
- Add GitHub Actions release workflow (push to main)
- Move system prompt to embedded markdown files
- Expand memory system: identity, soul, user profile, daily logs
- Pass system prompt through claude CLI --system-prompt flag
- Remove provider config from Config (prompts are file-based now)