The Node gate still expected three PurchaseTab slots (the title-bar entry
went when Purchases started following the section navigation) and a fixed
`z: 1` on the shell's NowPlayingBar (mode-aware since the 2.1.2
stabilization: Small's seek thumb needs the lift, the full-height modes
yield to the Large cover dock). test-crates on pre-release was red on the
second since the stabilization merge and would have failed on the first
next; both assertions now state the invariants that actually hold. 64
combinations x 3 sidebar states still prove exactly one reachable
Purchases entry.
cc