A 31-character pack ID makes mounted tile paths
(/sd/pyxis-map/packs/<id>/tiles/<z>/<x>/<y>.png) exceed the 68-byte mount
buffer once either x or y is two digits, so beginRead returns
INVALID_ARGUMENT and the UI shows 'Tile I/O error' at z4+ even though the
file exists and is intact.
Compiles the unmodified MapTilePack/MapTileStoreSD/SDAccess/codec/manifest
sources against small Arduino/FreeRTOS host shims. The core section (no
card needed) drives the real store with a model of the mount-prefix
arithmetic and asserts the 31-char-ID boundary loads at z4/z5; an optional
end-to-end section runs the real MapTilePack over a bound card root when
/sd is writable.
Fails on the current 64-byte PATH_CAPACITY: red by design.
