[fix] Map Mac keyboard geometry so ISO keycaps match in the guest

[jean-humann]

Summary

Mac ISO keyboards deliver Linux KEY_GRAVE and KEY_102ND swapped through Cocoa, so @# and <> land on the wrong keys in the guest (#67). Omarchy setup French|fr is PC fr, so even correct keycodes show ² above Tab.

This detects ANSI / ISO / JIS once in the compiled omarchy-vm-helper and fails the launch on an unknown Carbon class. The same value is exported as TRYOMARCHY_KEYBOARD and appended as tryomarchy.keyboard=. QEMU Cocoa swaps those keycodes only when the env is iso. Recovery QEMU unsets the env and does not append the token. The guest sets only kb_model=applealu_*. Macintosh legends apply to xkeyboard-config Mac vendor layouts (ch de dk fi fr gb is it latam nl no pt se us) with an empty variant; the ISO keycode correction applies to every layout.

On an M3 Pro French AZERTY ISO host, a factory guest built from this branch (lock used locally, not committed) applied kb_model=applealu_iso with no frmac. Physical above-Tab typed @ / # and the extra ISO key typed < / >.

The runtime patch is checksum-pinned and applies after the existing Cocoa series. The upstream QEMU pin is unchanged (qemu_commit=c3d48b7d1e89604920e5b81b91140c2ad39a1943). Review the hash against macos/build-qemu-gpu-runtime.sh (iso_swap_patch_sha256):

shasum -a 256 macos/patches/qemu-cocoa-iso-section-grave-swap.patch

Expected: 57f33a5fb08fb90a7813b13bb7037a13198e4d7db230085b1faa28b284cf2387.

See docs/mac-keyboard.md.

Existing VMs

App upgrade applies the Cocoa keycode swap immediately. That uninverts ISO @# / <> without kb_model. Remove any local frmac TLDE/LSGT workaround or those keys invert again. Macintosh legends need kb_model: dofile the overlay if a rebuilt image installed it, otherwise paste the hl.config snippet in docs/mac-keyboard.md. Do not dofile a missing path.

Test plan

On an Apple Silicon M3 Pro (French AZERTY ISO), 3d686d2:

• Patch SHA matches iso_swap_patch_sha256; QEMU pin unchanged
• make doctor / make test (Lua guest test + compiled ISO swap)
• make runtime — ISO patch applied last; staged macos/.build/qemu-gpu-runtime; TRYOMARCHY_KEYBOARD in QEMU
• omarchy-vm-helper --host-keyboard-geometry prints iso
• Factory guest from this branch (lock used locally, not committed): overlay + skel dofile present
• Ephemeral VM: TRYOMARCHY_KEYBOARD=iso, tryomarchy.keyboard=iso, kb_layout=fr, kb_model=applealu_iso, no frmac
• ISO FR physical keys: above Tab → @ / #; next to left Shift → < / >; keys do not invert
• ISO DE
• ANSI US (grave/tilde must not swap)
• Existing VM: remove frmac after upgrade

Related to #67.