Alkafirs Vertical Slabs

## Vertical Slabs 2.0.0 - Complete Rewrite

⚠️ **WARNING: NOT BACKWARDS COMPATIBLE** ⚠️
This is a full rewrite of the mod. Worlds using version 1.x will lose all placed vertical slabs and corners. Back up your world before updating.

### What Changed
- Complete architecture rewrite from the ground up
- Old system: 190+ registered blocks (one per material)
- New system: 2 blocks total with DataComponent-based material storage

### New Features
- **Proper ambient occlusion** — blocks now render through the chunk mesh pipeline with correct lighting and shadows, matching vanilla blocks
- **Automatic modded block support** — no more two-launch system. Modded blocks are detected via tags (c:storage_blocks, minecraft:planks, minecraft:wool) and slab-existence checks
- **Corner placement preview** — translucent 3D preview shows exactly what shape will be placed
- **Expanded block list** — wool, metal/gem blocks (iron, gold, diamond, emerald, netherite, etc.), all copper variants, glazed terracotta, obsidian, calcite, packed ice, and more
- **JEI integration** — all variants shown separately in JEI
- **Stonecutter recipes** — 1 block → 2 slabs or 2 corners
- **Crafting recipes** — 3 blocks vertical → 2 slabs, 6 blocks L-shape → 4 corners
- **Dynamic item rendering** — items in hand/inventory show the correct material texture

### Improvements
- Massively reduced block/item registration (from 190+ to 2)
- No more ModernFix resource pack workarounds
- Mining speed and sounds now properly match the base material
- Cleaner codebase, better performance
- Works with any full-cube solid block

### Known Issues
- Block break crack animation covers the full block area instead of just the slab shape (cosmetic only)
- Item icons use compressed texture due to scaling (functional, just visual)

### Corner Types
- **Inside** (quarter-block) — place in the 4 corner zones
- **Outside** (L-shape) — place in the 4 edge zones, shift+scroll to flip
- **T-Junction** — place in the center zone, shift+scroll to rotate
- **Centered** (centered-L) — available via center slab placement