corpseorigin

# Today's Update Highlights

## Fixes
- **Limb regrow animation not playing when wearing GeoLib armor**: Root cause was GeckoLib overwriting the player's render state with only the helmet's animation data. Fixed by writing limb data back via `GeoArmorRendererCaptureMixin`.
- **Model offset silently failing**: `cam.initialized` check was unreliable and the offset was hardcoded. Now uses model-pixel-based adaptive offset.
- **Broken drop chain**: Added drop tables for `zbr_flesh` block + 3 entities.
- **Survival unplayable**: Previously had 0 recipes and 0 natural spawning. Now fully implemented.

## Additions
- **Character selection book GUI**: Single unified book, consumed on selection, server-side validated, auto-granted once on survival start.
- **Ultraman Corpse Brother**: New entity reusing low-tier model, skips zombie skeleton bones, non-aggressive.
- **Survival content**: 12 recipes + 12 unlock advancements, 7 naturally spawning mobs, corpse water spring worldgen.
- **Corpse Brother appearance system**: Random player IDs + `api.mojang.com` skin resolution + local tint variants.
- **Config file** `config/corpseorigin.json`.

## Adjustments
- Lowered Corpse Brother spawn weights, concentrated spawning near corpse water springs.
- Removed all temporary `[LIMB-DBG]` debug logging.

## TODO
- Skin resolution may fail in China; needs CustomSkinLoader fallback.