chore: bump version to 6.0.0-alpha.17 with comprehensive changelog

Major improvements include:
- Revolutionary installer overhaul with unified flow for core and custom modules
- Full custom content support re-enabled with streamlined sharing
- Critical migration from .bmad to _bmad for AI visibility
- Agent memory system rollout with _bmad/_memory location
- Quick default selection for faster module installation
- BMM Phase 4 workflow improvements and standardization
- Sample modules demonstrating custom content creation
- Future-ready architecture for content segregation

package.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://json.schemastore.org/package.json",
   "name": "bmad-method",
-  "version": "6.0.0-alpha.16",
+  "version": "6.0.0-alpha.17",
   "description": "Breakthrough Method of Agile AI-driven Development",
   "keywords": [
     "agile",