Bootloader hardcoded RedoxFS partition offset at 2 MiB, which fails when
efi_partition_size > 1 (redbear-full, redbear-grub use 16 MiB, placing
RedoxFS at LBA 34816 = 17 MiB). Added GPT partition table parser that
scans for Linux filesystem GUID (0FC63DAF) to find the actual offset.
Also removed invalid 'respawn = true' from 31_debug_console.service in
redbear-full.toml — init's service format does not support this field.
Verified: all three ISOs boot in QEMU UEFI and reach login prompt.
