bind upstream get_multi APIs, replace sized-struct Info()
Update the pinned ghostty commit to pick up the new _get_multi C
APIs added across all getter types (terminal, render state, row,
cell, screen, kitty graphics image, kitty graphics placement).
The existing Info() methods on KittyGraphicsImage and
KittyGraphicsPlacementIterator previously used sized-struct C
types (GhosttyKittyGraphicsImageInfo, etc.) initialized via
GHOSTTY_INIT_SIZED. These are replaced by get_multi calls that
fetch each field individually through typed pointers, eliminating
struct ABI concerns (padding, alignment, field ordering) at the
cgo boundary. The Go-side convenience structs remain unchanged.
Each type also gains a public GetMulti method that exposes the
raw get_multi API for callers who want to batch arbitrary subsets
of queries into a single cgo crossing.
A shared cValuesArray helper in get_multi.go solves the cgo
pointer-passing rule for void**: the array of output pointers is
allocated in C heap memory, populated from Go, passed to C, then
freed.