Node 20, installer improvements, agent improvements and Expansion Pack for game dev (#232)

* feat: add expansion pack installation system with game dev and infrastructure expansion packs

- Added expansion pack discovery and installation to BMAD installer
- Supports interactive and CLI installation of expansion packs
- Expansion pack files install to destination root (.bmad-core)
- Added game development expansion pack (.bmad-2d-phaser-game-dev)
  - Game designer, developer, and scrum master agents
  - Game-specific templates, tasks, workflows, and guidelines
  - Specialized for Phaser 3 + TypeScript development
- Added infrastructure devops expansion pack (.bmad-infrastructure-devops)
  - Platform engineering agent and infrastructure templates
- Expansion pack agents automatically integrate with IDE rules
- Added list:expansions command and --expansion-packs CLI option

🤖 Generated with Claude Code

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

* alpha expansion packs and installer update to support installing expansion packs optionally

* node20

---------

Co-authored-by: Brian Madison <brianmadison@Brians-MacBook-Pro.local>
Co-authored-by: Claude <noreply@anthropic.com>

expansion-packs/bmad-2d-phaser-game-dev/agent-teams/team-game-dev.yml

@@ -0,0 +1,12 @@
+bundle:
+  name: Game Development Team
+  icon: 🎮
+  description: Comprehensive game development team specialized in 2D games using Phaser 3 and TypeScript. This team handles the complete game development lifecycle from initial concept brainstorming through detailed design documentation to technical implementation and quality assurance. Specializes in indie games, mobile games, web games, educational games, prototyping, and game feature development with focus on player experience and performance optimization.
+agents:
+  - bmad-orchestrator
+  - game-designer
+  - game-developer
+  - game-sm
+workflows:
+  - game-dev-greenfield
+  - game-prototype