🎯 /feature intake hardening — read the issue body + re-validate aged scope

[PierreBrisorgueil]

The /feature skill's Phase 0.0 claim step fetches an issue's number,title,state,assignees,comments — but not its body. The scope written in the issue description is never loaded by the executor. Phase 0.0 also has no staleness gate: an aged issue is implemented as-written even when the code it references has since moved.

Sub-issues track the same change in each stack repo:

• fetch body in Phase 0.0 and treat it as the primary scope source
• aged-scope gate: issue older than ~7 days, or body references that no longer match the codebase → re-validate scope against current code and present the drift before implementing

Created via /dev:issue

[PierreBrisorgueil]

All sub-issues merged: Node#3928 (PR #3929) + Vue#4394 (PR #4396). /feature Phase 0.0 body-fetch + aged-scope gate now on both stack repos. Complete.