[ZeroPoint95]

Changes

• internal/furrow now names FURROW_DATA_DIR=/furrow on every furrow child inside runBinary — the sole spawn seam — only when the environment does not already set it, so two profiles that share a HOME no longer share one snapshot store and deliberate overrides survive.
• On first start of the new layout, a furrow store an older build left in the platform data root (~/Library/Application Support/dev.furrow.furrow) is moved once into the default profile's furrow/store-v1, with a relative link left at the old path so an older binary still resolves the same store; the help env CODEAF_HOME row now names the store.
• A new key-gated e2e lane (TestTheFurrowStoreFollowsTheStateRoot) asserts, behind the host guard's throwaway HOME, that a session leaves the snapshot store under CODEAF_HOME/furrow/store-v1 and nothing under the login's data root; a changelog entry records the move.
• Final change: 7 files, +400/−3.

Closes #1769.

Validation

• Passed locally: cd . && go test ./internal/home/ -count=1 2>&1 | tail -2; echo "home-exit=${PIPESTATUS[0]}"; go test ./internal/session/ -run Furrow -count=1 2>&1 | tail -2; echo "session-exit=${PIPESTATUS[0]}".
• Passed locally: cd . && go test -tags e2e -run FurrowStore ./internal/e2e/ -count=1 -v 2>&1 | tail -8; echo "e2e-exit=${PIPESTATUS[0]}".
• Proof · 8 of 8 claims shown locally. GitHub CI is checked after publishing.
• ✓ runBinary gives every furrow child FURROW_DATA_DIR under the state root and preserves a caller-set value
• ✓ adoption moves a legacy platform-root store into the default profile once, idempotently, with the review-added compatibility link
• ✓ boot calls furrow.Adopt after home.Adopt

by codeaf factory

Factory-Approval: evt_a35762c1 @ZeroPoint95 e003cfe