Add DeltaNet

[AntonOresten]

Created from a single prompt to Opus, with https://github.com/RightNow-AI/qwen3.5-triton as reference. Only skimmed the code and it's alright but needs testing. Would be fun to optimize inference for the dense Qwen 3.5 models in Julia.

Closes #23

[codecov]

Codecov Report

❌ Patch coverage is 30.13100% with 160 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.42%. Comparing base (91a8d3b) to head (5302073).

Files with missing lines	Patch %	Lines
ext/cuTileExt/kernels/recurrent/deltanet.jl	0.00%	44 Missing ⚠️
ext/cuTileExt/kernels/recurrent/causal_conv1d.jl	0.00%	33 Missing ⚠️
ext/cuTileExt/bindings/feedforward/swiglu.jl	0.00%	19 Missing ⚠️
src/utils/inplace.jl	0.00%	16 Missing ⚠️
ext/cuTileExt/bindings/linear.jl	0.00%	9 Missing ⚠️
ext/cuTileExt/bindings/recurrent/causal_conv1d.jl	0.00%	8 Missing ⚠️
ext/cuTileExt/bindings/recurrent/deltanet.jl	0.00%	8 Missing ⚠️
src/fuse.jl	12.50%	7 Missing ⚠️
ext/cuTileExt/bindings/attention/attention.jl	0.00%	6 Missing ⚠️
src/primitives/recurrent/deltanet.jl	73.68%	5 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #54      +/-   ##
==========================================
- Coverage   39.94%   39.42%   -0.52%     
==========================================
  Files          73       82       +9     
  Lines        2789     2970     +181     
==========================================
+ Hits         1114     1171      +57     
- Misses       1675     1799     +124     

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