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/tasks/doc-migration-task.md

@@ -0,0 +1,143 @@
+# Document Migration Task
+
+## Purpose
+
+Simple document migration that cleans up heading formats and adds epic structure for PRDs.
+
+## Task Requirements
+
+1. **Input**: User specifies the document to migrate (e.g., `docs/prd.md`)
+2. **Detection**: Automatically determine if it's a PRD or other document type
+3. **Migration**: Apply appropriate transformations
+4. **Backup**: Create backup with `.bak` extension
+
+## Migration Rules
+
+### For PRDs
+
+- Find all level 3 headings that appear to be epics
+- Add a level 2 heading "## Epic #" (incrementing number) before each epic
+- Also apply the heading cleanup rules below
+
+### For All Documents
+
+- Find all level 2 headings (`## ...`)
+- Remove leading numbers and symbols
+- Keep only alphabetic characters and spaces
+- **CRITICAL**: Do not lose any information - preserve all content under appropriate headings
+- Examples:
+  - `## 1. Foo & Bar` → `## Foo Bar`
+  - `## 2.1 Technical Overview` → `## Technical Overview`
+  - `## 3) User Experience` → `## User Experience`
+
+### For Architecture Documents
+
+- **PRIMARY GOAL**: Align level 2 headings to match template level 2 titles exactly
+- **PRESERVE EVERYTHING**: Do not lose any information during migration
+- Map existing content to the closest matching template section
+- If content doesn't fit template sections, create appropriate level 3 subsections
+
+## Detection Logic
+
+A document is considered a PRD if:
+
+- Filename contains "prd" (case insensitive)
+- OR main title contains "Product Requirements" or "PRD"
+- OR contains sections like "User Stories", "Functional Requirements", "Acceptance Criteria"
+
+## Implementation Steps
+
+1. **Backup Original**: Copy `filename.md` to `filename.md.bak`
+2. **Detect Type**: Check if document is a PRD
+3. **Process Headings**:
+   - Clean all level 2 headings
+   - If PRD: Add epic structure before level 3 headings that look like epics
+4. **Write Result**: Overwrite original file with migrated content
+
+## Epic Detection for PRDs
+
+Level 3 headings are treated as epics if they:
+
+- Describe features or functionality
+- Are substantial sections (not just "Overview" or "Notes")
+- Common epic patterns: "User Management", "Payment Processing", "Reporting Dashboard"
+
+The epic numbering starts at 1 and increments for each epic found.
+
+## Example
+
+### Before (PRD):
+
+`````markdown
+# Product Requirements Document
+
+## 1. Executive Summary
+
+Content here...
+
+## 2.1 Functional Requirements & Specs
+
+Content here...
+
+### User Management System
+
+Epic content...
+
+### Payment Processing
+
+Epic content...
+
+## 3) Success Metrics
+
+Content here...
+
+````text
+
+### After (PRD):
+```markdown
+# Product Requirements Document
+
+## Executive Summary
+Content here...
+
+## Functional Requirements Specs
+Content here...
+
+## Epic 1
+### User Management System
+Epic content...
+
+## Epic 2
+### Payment Processing
+Epic content...
+
+## Success Metrics
+Content here...
+```text
+
+### Before (Non-PRD):
+```markdown
+# Architecture Document
+
+## 1. System Overview
+Content...
+
+## 2.1 Technical Stack & Tools
+Content...
+```text
+
+### After (Non-PRD):
+```markdown
+# Architecture Document
+
+## System Overview
+Content...
+
+## Technical Stack Tools
+Content...
+````
+`````
+
+```text
+
+```