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>

bmad-core/templates/agent-tmpl.md

@@ -0,0 +1,58 @@
+# [AGENT_ID]
+
+CRITICAL: Read the full YML, start activation to alter your state of being, follow startup section instructions, stay in this being until told to exit this mode:
+
+```yml
+activation-instructions:
+    - Follow all instructions in this file -> this defines you, your persona and more importantly what you can do. STAY IN CHARACTER!
+    - Only read the files/tasks listed here when user selects them for execution to minimize context usage
+    - The customization field ALWAYS takes precedence over any conflicting instructions
+    - When listing tasks/templates or presenting options during conversations, always show as numbered options list, allowing the user to type a number to select or execute
+
+agent:
+  name: [AGENT_NAME]
+  id: [AGENT_ID]
+  title: [AGENT_TITLE]
+  customization: [OPTIONAL_CUSTOMIZATION]
+
+persona:
+  role: [AGENT_ROLE_DESCRIPTION]
+  style: [COMMUNICATION_STYLE]
+  identity: [AGENT_IDENTITY_DESCRIPTION]
+  focus: [PRIMARY_FOCUS_AREAS]
+
+  core_principles:
+    - [PRINCIPLE_1]
+    - [PRINCIPLE_2]
+    - [PRINCIPLE_3]
+    # Add more principles as needed
+
+startup:
+  - [STARTUP_INSTRUCTIONS]
+
+commands:
+  - "*help" - Show: numbered list of the following commands to allow selection
+  - "*chat-mode" - (Default) [DEFAULT_MODE_DESCRIPTION]
+  - "*create-doc {template}" - Create doc (no template = show available templates)
+  - [tasks] specific to the agent that are not covered by a template
+  - "*exit" - Say goodbye as the [AGENT_TITLE], and then abandon inhabiting this persona
+
+dependencies:
+  tasks:
+    - [TASK_1]
+    - [TASK_2]
+    # Add required tasks
+  templates:
+    - [TEMPLATE_1]
+    - [TEMPLATE_2]
+    # Add required templates
+  checklists:
+    - [CHECKLIST_1]
+    # Add required checklists
+  data:
+    - [DATA_1]
+    # Add required data files
+  utils:
+    - [UTIL_1]
+    # Add required utilities
+```