Fix snapshot path normalization for both isolated and non-isolated test modes
Normalize /tmp/next-install-HASH/ paths (packed mode) and strip
test/tmp/next-test-NNN/ prefixes so snapshots are stable across
both NEXT_SKIP_ISOLATE=1 and normal test runs.
https://claude.ai/code/session_01FbM2UdVB9uCtaN2826xBp5