M9.R.37.7: GRUB menu on serial console so headless QEMU boot succeeds

The runMinimalBootstrap GRUB config wrote set timeout=5 + a single
ReproOS menuentry but no serial terminal config.  Consequence: on a
headless QEMU run (-nographic -serial mon:stdio), GRUB renders the menu
on the framebuffer ONLY, and since the framebuffer doesn't exist, the
serial console sees nothing.  The 5s timeout ticks down internally but
no boot ever triggers AND no key event reaches GRUB.  Stage-2 boot
hangs in GRUB indefinitely.

Fix: wire GRUB's UI to BOTH the console AND ttyS0 via

  serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
  terminal_input console serial
  terminal_output console serial
  set timeout_style=hidden
  set timeout=3

timeout_style=hidden skips the interactive menu entirely (no risk
of the FIFO driver's idle input typing into edit mode), and 3s is
enough for a serial console to settle.

Also bump _m9r37_boot_installed.sh's sleep from 90s to 150s so the FIFO
input lands after the installed system reaches the login prompt, not
during early kernel init.

Author: zah

_m9r37_boot_installed.sh

@@ -27,7 +27,13 @@ date
 BOOT_FIFO="$(mktemp -d)/boot-in.fifo"
 mkfifo "$BOOT_FIFO"
 (
-  sleep 90
+  # GRUB defaults to a 5s timeout + auto-boots the first entry; any
+  # keystroke during the menu (even an idle "root\n" from this FIFO)
+  # interrupts the timeout and the menu sits forever.  Sleep through
+  # the GRUB timeout + boot + login prompt before sending anything.
+  # M9.R.36 used sleep 90 here; bump to 150 to be safe in case the
+  # OVMF firmware adds a "Press any key to continue" extra step.
+  sleep 150
   echo "root"
   sleep 3
   echo "reproos"

apps/reproos-installer/src/installer_state.cpp

@@ -600,8 +600,21 @@ void InstallerState::runMinimalBootstrap(const QString &target) {
        "/boot --boot-directory=" + target +
        "/boot --no-nvram --removable --recheck " + grubDevice, 120000);
     appendLog("Phase 5e: writing GRUB config");
+    // M9.R.37.7 — wire the GRUB UI to BOTH console (tty1) AND serial
+    // (ttyS0) so headless QEMU runs see the menu + boot countdown
+    // tick.  Without ``serial --unit=0`` + ``terminal_input/_output
+    // serial console`` GRUB renders the menu on the framebuffer ONLY
+    // — which on ``qemu -nographic -serial mon:stdio`` is invisible —
+    // and the timeout ticks but no key event ever reaches GRUB.  A
+    // ``set timeout_style=hidden`` together with ``set timeout=3``
+    // also bypasses the interactive menu entirely on serial-only
+    // hardware (matching Debian's serial-installer pattern).
     QString grubCfg =
-        "set timeout=5\n"
+        "serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1\n"
+        "terminal_input console serial\n"
+        "terminal_output console serial\n"
+        "set timeout_style=hidden\n"
+        "set timeout=3\n"
         "set default=0\n"
         "menuentry 'ReproOS' {\n"
         "  linux /boot/vmlinuz root=/dev/vda2 ro console=tty1 console=ttyS0,115200\n"