dev clone: host-global builtin cloning via gh auth to the canonical $DEV_CD_ROOT path

[d3mlabs-ai-flow]

Part of d3mlabs/plans#26.

[JPDuchesne]

/build

✅ /build — opened #107

🧠 drafted 3 learnings in a learning proposal PR: #108

• command-dispatch
• module-map
• data-define-nested-constants

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⚙️ workflow run · model: claude-fable-5-high