Twelve login terminals, root only, console fixes, a faster build, a Niveus splash, and X back on evdev

- tty1-tty12 all run login; the image has only root. /dev/tty7..12 could not
  be written (cdev.c knew minors 10-16 only), which sent their jobs into a
  restart storm that took the supervisor down; fixed, and stat reports them as
  Linux's tty7..12.
- Erasing text at a prompt did nothing: erase_one sent a bare backspace, which
  only moves; it and the echo path now send back-blank-back through vt_feed.
- A white cursor block was left at the end of every line of a verbose boot:
  a line feed at the bottom scrolls the pixels, cursor included, and the
  cursor was erased after the scroll. It comes off first now. A blank cell is
  also marked dirty, which it was not.
- ldlsd died with a general protection fault on real hardware in its variadic
  log function: Linux module code calls with an 8-byte-aligned stack and an
  unset %al, and the prologue's movaps faults. LDLS guest code is built with
  -mstackrealign.
- make iso took over a minute for any change, because staging r8169 rewrote
  the same files and every mtime moved; it now replaces files only if their
  contents differ (about 10 s).
- The loader's splash is redrawn in the boot manager's style, and the boot
  manager shows its cursor whenever a pointer device exists.
- xf86-input-libinput is out of the image again: with it Xorg took both
  keyboard and pointer from libinput and, on the user's laptop, neither worked.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EVRhxi9zpdW2uDUN4FVcao

docs/architecture/users.md

@@ -6,15 +6,15 @@ the part that makes it a multi-user system.
 
 ## What you meet
 
-- **`login` on tty1–tty5.** `etc/schos-getty` takes the terminal back from
-  whoever had it and runs `login`, which asks who is there and starts their
-  shell; when the shell exits `schinit` starts the prompt again.
-- **tty6 is a root shell with no login**, on purpose: the way in when login
-  itself is what is broken.
-- **Two accounts in the image.** `root`, and `schos` (uid 1000, home
-  `/home/schos`, in `wheel tty video input audio cdrom`). Both have empty
-  passwords, so `login` lets them in without asking — it is a live image.
-  `passwd` sets one.
+- **`login` on all twelve terminals, tty1–tty12.** `etc/schos-getty` takes the
+  terminal back from whoever had it and runs `login`, which asks who is there
+  and starts their shell; when the shell exits `schinit` starts the prompt
+  again. Alt+F1…F12 (or Ctrl+Alt+F1…F12) switches between them. (There is no
+  longer a login-free root shell on tty6.)
+- **One account in the image: `root`**, with an empty password, so `login` lets
+  it in without asking — it is a live image. `passwd` sets one. More users are
+  an `adduser` away; `wheel` is empty, so `su` and `doas` have no one to serve
+  until then.
 - **`su` and `passwd`** (`cmd/su`, `cmd/passwd`) are setuid root and small
   programs of their own, not toybox applets: toybox is one binary under every
   name, and a setuid copy of it can be asked for any applet by naming it, as
@@ -61,8 +61,8 @@ kernel's devices with the answers the kernel gave.
 
 Everything in the image is owned by root: the build host's user means nothing
 inside it. `mkschfs --owners FILE` takes the exceptions, one `path uid gid
-[mode]` per line (`tools/posix/mkaroot.sh` writes it: `/home/schos 1000 1000
-0700`, and the modes of `/tmp`, `/var/tmp` and `/root`). The setuid bits are set
+[mode]` per line (`tools/posix/mkaroot.sh` writes it: the modes of `/tmp`,
+`/var/tmp` and `/root`). The setuid bits are set
 on `su`, `passwd` and `doas` in the root tree directly, because `apk` run as an
 ordinary user may have dropped them.