Finish Package Freeze And Replacement Truth Macro

Goal

• Close Macro Task 4 at the planning layer.

Scope

• Freeze slate-dom, slate-react, slate-history, and slate-browser stable surfaces explicitly.
• Refresh the replacement-truth docs and final stop/go read.
• Mark the roadmap macro program complete enough to freeze.

Phases

• Freeze the package surface boundaries in roadmap/package docs
• Refresh replacement-truth docs and final stop/go wording
• Mark Macro Task 4 done enough and verify the touched docs