## What's New
Add Split-N support for grouped convolution forward to handle tensors >2GB by splitting the batch dimension.
## Bug Fix
Fixed 32-bit integer overflow that caused crashes with 6+ splits:
- Use `long_index_t` for batch offset calculations
- Remove redundant GemmM initialization in constructors
## How It Works
- Automatically splits batch dimension when tensor exceeds 2GB
- Uses grid.z dimension for parallel processing of splits
- Each split processes a subset of batches independently
## Testing
Verified with tile_example_grouped_conv_fwd:
- n=3000 (6 splits) ✓
- n=3500 (7 splits) ✓
- n=10480 (40 splits) ✓
* base working version for single groupped conv bwd data
* Fix 2d descriptor
* fix groups
* Add 3d support
* fixes
* fixes
* fixes
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Co-authored-by: Jakub Piasecki <jakpia21@gmail.com>
