v4-v6 upgrade improvement and warning about file auto backup

bmad/bmm/teams/team-all.yaml

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+# <!-- Powered by BMAD-CORE™ -->
+bundle:
+  name: Team All
+  icon: 👥
+  description: Includes every bmm system agent.
+agents:
+  - "*"

bmad/bmm/teams/team-dev.yaml

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+# <!-- Powered by BMAD-CORE™ -->
+bundle:
+  name: Team Fullstack
+  icon: 🚀
+  description: Team capable of full stack, front end only, or service development.
+agents:
+  - analyst
+  - pm
+  - ux-expert
+  - architect
+  - po
+  - tea
+  - devops
+  - security

bmad/bmm/teams/team-gamedev.yaml

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+# <!-- Powered by BMAD-CORE™ -->
+bundle:
+  name: Team Game Development
+  icon: 🎮
+  description: Specialized game development team including Game Designer (creative vision and GDD), Game Developer (implementation and code), and Game Architect (technical systems and infrastructure). Perfect for game projects across all scales and platforms.
+agents:
+  - game-designer
+  - game-dev
+  - game-architect