Closes N100 F1 (HIGH): cheap AMI (AN3PLUS 0.01-class) UEFI firmware can't
relocate the ISO's stock signed GRUB from USB (relocation 0x0). The run's live
grub-mkimage workaround is now a first-class pipeline mode.
- build-felhom-iso.sh: --loader shim|mkimage (default shim, byte-for-byte
unchanged; profile-settable FELHOM_LOADER; --loader wins). Loud banner +
manifest loader:/grub-mkimage: fields + -mkimage filename suffix.
- mkimage-surgery.sh (new): post-prepare-iso, in the assistant container. Builds
a monolithic grub-mkimage loader from the ISO's own GRUB (module set from its
grub.cfg; embedded search --fs-uuid -> configfile the real menu). Swaps it into
the ISO9660 tree (real lowercase path) + the efi.img ESP; xorriso re-master
preserves BIOS-hybrid + UEFI + GPT-ESP, drops only Apple HFS+/APM. Recipe from
the N100 run evidence, not re-derived.
- Dockerfile.assistant: grub-common + grub-efi-amd64-bin + mtools + dosfstools.
profiles/n100.profile (new, mkimage + SB-off note).
- Validated on nested VM 311 (RUNBOOK-B legs): leg1 shim boots+installs under
OVMF SB-enforcing + SeaBIOS; leg2 mkimage boots+installs under SB-off; leg3
(red-proof) mkimage under SB-enforcing FAILS Access Denied (unsigned -> SB must
be OFF); leg4 surgery byte-identical payload. bash -n + shellcheck clean.
Physical N100 closure folds into the rehearsal (n100-safety match-nothing ISO
built + sha-recorded, unbooted). PXE stays a deferred R-21 note.
