v1.5.2 — shell codegen fatal eliminated

Source + bundle release clearing the README's last known issue. Bundles for all three platforms were restaged from this tag the same day the repository went public; the Steam Deck build was boot-verified on the device.

• The shell's only codegen fatal is gone. The long-standing known issue — a split block at 0x82081778 whose branch back into sub_82081658's loop could not be expressed — rested on a pointer-scan false positive: the only pointer to that address in the whole image is a lwz r16,0x1778(r8) instruction whose encoding aliases the address. The address is now declared a chunk of its parent in futari_functions.toml, and the vendored SDK's half-built chunk mechanism was completed to honour it: a chunk claims its range (suppressing the PDATA, exception-handler, gapfill, and pointer-scan paths from re-splitting it) without emitting a function, a dispatch entry, or the fatal. The scans warn when they skip a chunk-claimed address, so a genuine dispatch table pointing at a chunk would surface rather than vanish. The generated shell changes by exactly one removed function; boot-verified with all 8 modules registering cleanly.

See CHANGELOG.md for details.