Fix memory corruption and support WinPE

[eransha-salvador]

Two distinct issues surface when running sshd on WinPE (a restricted
Windows environment with no user-profile service and no desktop /
window-station for non-interactive users). Both crash the daemon before
the user can log in.

1. load_user_profile format-string mismatch.
   The debug3 call on LoadUserProfileW failure declares
   "%s %S %d" (three specifiers) but passes only two arguments. %S
   consumes GetLastError()'s DWORD as a wide-string pointer, then
   wcsnlen dereferences it and crashes sshd-session post-auth. Only
   visible where LoadUserProfileW actually fails (e.g. WinPE, which
   has no user-profile service), so stock Windows was unaffected.

2. sshd-auth crashes on restricted window stations.
   sshd-auth is a privsep helper spawned as a different user and runs
   without desktop / window-station access. user32.dll's DllMain
   binds to the process window station and fails with
   STATUS_DLL_INIT_FAILED in restricted environments, so the helper
   dies before auth begins. The only transitive user32 references in
   sshd-auth come from console.c's ConRestoreViewRect_NoPtyHack
   (ShowWindow / GetWindowPlacement), which sshd-auth does not execute.
   Delay-loading user32 is sufficient: the DLL is never loaded in
   practice.

Depends on #2434 (shared build changes).