Three related issues where User().ID() is called on potentially tagged
nodes without first checking IsTagged():
1. compileACLWithAutogroupSelf: the autogroup:self block at line 166
lacks the !node.IsTagged() guard that compileSSHPolicy already has.
If a tagged node is the compilation target, node.User().ID() may
panic. Tagged nodes should never participate in autogroup:self.
2. compileSSHPolicy: the IsTagged() check is on the right side of &&,
so n.User().ID() evaluates first and may panic before short-circuit
can prevent it. Swap to !n.IsTagged() && n.User().ID() == ... to
match the already-correct order in compileACLWithAutogroupSelf.
3. invalidateAutogroupSelfCache: calls User().ID() at ~10 sites
without IsTagged() guards. Tagged nodes don't participate in
autogroup:self, so they should be skipped when collecting affected
users and during cache lookup. Tag status transitions are handled
by using the non-tagged version's user ID.
Fixes#2990
1f32c8bf61