fix: GRUB theme font refs, improve QEMU test script

Theme: remove explicit font name references that don't match
grub-mkfont output names, remove select_*.png pixmap reference
(files don't exist). GRUB falls back to default when theme fails
to load — this was causing the Debian helmet to show.

QEMU test script: add --bios/--nographic flags, serial console
logging to /tmp/archipelago-qemu-serial.log, auto-detect latest
ISO, use -drive for OVMF firmware.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

image-recipe/branding/grub-theme/theme.txt

@@ -1,20 +1,17 @@
 # Archipelago GRUB Theme
 # Dark background with Bitcoin orange accents
+# Font references removed — GRUB uses whatever fonts are loaded in grub.cfg
 
 title-text: ""
 desktop-color: "#0a0a0a"
-terminal-font: "DejaVu Sans Regular 16"
 
 + boot_menu {
     left = 25%
     top = 40%
     width = 50%
     height = 30%
-    item_font = "DejaVu Sans Regular 16"
     item_color = "#aaaaaa"
-    selected_item_font = "DejaVu Sans Regular 16"
-    selected_item_color = "#ffffff"
-    selected_item_pixmap_style = "select_*.png"
+    selected_item_color = "#f7931a"
     item_height = 36
     item_spacing = 8
     item_padding = 16
@@ -26,7 +23,6 @@ terminal-font: "DejaVu Sans Regular 16"
     top = 20%
     width = 50%
     text = "A R C H I P E L A G O"
-    font = "DejaVu Sans Bold 24"
     color = "#f7931a"
     align = "center"
 }
@@ -36,7 +32,6 @@ terminal-font: "DejaVu Sans Regular 16"
     top = 28%
     width = 50%
     text = "Bitcoin Node OS"
-    font = "DejaVu Sans Regular 14"
     color = "#888888"
     align = "center"
 }
@@ -46,7 +41,6 @@ terminal-font: "DejaVu Sans Regular 16"
     top = 90%
     width = 50%
     text = "Use arrow keys to select, Enter to boot"
-    font = "DejaVu Sans Regular 12"
     color = "#555555"
     align = "center"
 }