X on the console: /dev/tty0, a palette, and startx that works

Xorg finds its VT through /dev/tty0, and without one ran on none: the
console went on drawing into the framebuffer over the X screen. tty0 is
the terminal on screen, as on Linux. FBIOPUTCMAP succeeds, as it does on
a true-colour Linux framebuffer, instead of 256 logged errors per start.

schos-base gives root a .xserverrc with -dumbSched, Xorg's switch for
input on the main loop: SchOS has no threads, and Xorg crashed in
pthread_join on its input thread when the first client left. It adds
the hostname to /etc/hosts, so xauth can resolve schos:0.

zsh loses PROMPT_SP: on a serial terminal narrower than the console its
padding wrapped and left a # above every prompt. bootcheck knows zsh's
prompt and matches without colour codes, so busybox's ls reads as text.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

include/gfx/fb.h

@@ -19,6 +19,7 @@
 #define FBIOGET_VSCREENINFO 0x4600
 #define FBIOPUT_VSCREENINFO 0x4601
 #define FBIOGET_FSCREENINFO 0x4602
+#define FBIOPUTCMAP         0x4605
 #define FBIOBLANK           0x4611
 #define FBIOPAN_DISPLAY     0x4606