feat(serial): headless serial console for mini/bare via fbcond mirror

Track base e9342b78 (fbcond bidirectional serial mirror) + kernel 229046c6
(debug fevent readable). Disable the standalone 31_debug_console getty since
fbcond now owns the serial/debug console (avoids competing for the shared debug
input queue and duplicated output). Gives headless serial login on mini + bare.

config/minimal.toml

@@ -47,16 +47,16 @@ type = "oneshot_async"
 
 [[files]]
 path = "/etc/init.d/31_debug_console.service"
+# The serial/debug console is now driven by fbcond, which mirrors the
+# framebuffer console (boot log + getty login prompt) onto the kernel debug
+# (serial) line and feeds serial input back into the same VT getty. A separate
+# `getty /scheme/debug/no-preserve` would compete with fbcond for the single
+# shared debug input queue and duplicate output, so it is disabled.
 data = """
 [unit]
-description = "Debug console"
-requires_weak = [
-    "29_activate_console.service",
-    "00_ptyd.service",
-]
+description = "Debug console (handled by fbcond serial mirror)"
 
 [service]
-cmd = "getty"
-args = ["/scheme/debug/no-preserve", "-J"]
-type = "oneshot_async"
+cmd = "true"
+type = "oneshot"
 """

config/redbear-mini.toml

@@ -546,18 +546,14 @@ type = "oneshot_async"
 
 [[files]]
 path = "/etc/init.d/31_debug_console.service"
+# Serial/debug console handled by fbcond's serial mirror (see minimal.toml).
 data = """
 [unit]
-description = "Debug console"
-requires_weak = [
-    "29_activate_console.service",
-    "00_ptyd.service",
-]
+description = "Debug console (handled by fbcond serial mirror)"
 
 [service]
-cmd = "getty"
-args = ["/scheme/debug/no-preserve", "-J"]
-type = "oneshot_async"
+cmd = "true"
+type = "oneshot"
 """
 
 [[files]]