laravel/framework: Middleware priority fix: appendToPriorityList() now works when the anchor is the first item
Pull request #61567 fixes a silent ordering bug in Kernel::addToMiddlewarePriorityRelative(), the engine behind appendToPriorityList(). When the middleware you anchored to was the first entry of the priority list, the new middleware was appended to the very end instead of right after it — with no warning. The array form also produced order-dependent results for adjacent references. If you are upgrading from v12.70.0 into 13.x, middleware registered through the priority list may now run earlier than before, which is the intended behavior, but it deserves a quick audit.
