feat: add Docker Cursor plugin with rules, agent, skills, hooks, and MCP config master
- .cursor/plugin.json: Plugin manifest with metadata and paths - rules/dockerfile-best-practices.mdc: Multi-stage builds, pinned versions, non-root users, layer optimization, HEALTHCHECK, COPY vs ADD - rules/docker-compose.mdc: Named volumes, explicit networks, resource limits, healthchecks, env files, image pinning, depends_on conditions, profiles - agents/docker-optimization-agent.md: Image optimization, build performance, security hardening analysis agent - skills/create-dockerfile/SKILL.md: Language-specific Dockerfile templates (Node.js, Python, Go, Java, Rust) with multi-stage builds - skills/setup-docker-compose/SKILL.md: Dev environment setup with hot-reload, databases, caching, monitoring, and production overrides - hooks/hooks.json: Pre-commit hooks for Hadolint, Compose validation, .dockerignore checks, and secret scanning - mcp.json: Docker MCP server for container/image management operations - scripts/lint-dockerfile.sh: Hadolint wrapper with auto-detection - README.md, CHANGELOG.md, LICENSE (MIT 2026 Cursor) Co-authored-by: n2parko <n2parko@users.noreply.github.com>