Fix: /back onto nether roof exploit when destination is unsafe. - #6602

EssentialsX@d2a7e0f Update paperVersion to 26.2.build.92-stable (EssentialsX#6575)
EssentialsX@f6f13fd Show muted players' private messages to social spies (EssentialsX#6569)
EssentialsX@382de4f Fix: /back onto nether roof exploit when destination is unsafe. (EssentialsX#6602)

This reverts commit 1fcbec7. The bump was WRONG: 28eb89f ("Add toolchain
auto download EssentialsX#6574", 2026-06-16) is not newer than 382de4f - it is a
side-branch commit two months older, and 382de4f IS the current
EssentialsX/Essentials 2.x tip (verified: git rev-parse origin/2.x ==
382de4f, and rev-list 28eb89f..382de4f == 6 while 382de4f..28eb89f == 1).

Root cause: I read 'git diff Essentials' backwards - the '-Subproject commit
382de4f' side was the correct COMMITTED pin and '+28eb89fb0' was a stale
working-tree checkout, which I mistook for a new upstream. The build number
falling from dev+37 to dev+31 was the signal that this was a downgrade, and I
rationalised it instead of checking.

The downgrade dropped six real upstream commits, including the /back
nether-roof exploit fix (EssentialsX#6602), social-spy visibility of muted players'
private messages (EssentialsX#6569), paperVersion 26.2.build.92-stable (EssentialsX#6575) and the
cached online-user lookup optimisation (EssentialsX#6595).