This replaces per-weight instantiations of all code with only per-MatMul/norm.
Reduces binary size by 133KiB.
WeightsOwner is no longer required for type erasing, hence it is replaced with ModelWeightsPtrs.
Also remove unused EmbedToken, replaced with EmbedMMToken.
PiperOrigin-RevId: 766497657
Weight handling:
- new ModelStore2 supports both pre-2025 multi-file and single-file formats
- simpler ForEachTensor with TensorArgs
- tensors are constructed with their full suffixed name
I/O:
- support mmap and stride
- Simplified SbsWriter, single insert(); add SbsReader
Misc:
- kMockTokenizer: allow creating with unavailable tokenizer
- configs.h: Simpler enum validity checks via kSentinel
- matmul.h: remove unused enable_bind (now in allocator.h)
- tensor_info: single TensorInfoRegistry class, rename from tensor_index.h
Frontends:
- Replace Allocate/CreateGemma with ctor(LoaderArgs, MatMulEnv&)
- Deduce model/weight type, remove --model and parsing
- Replace most common.h includes with configs.h
- Remove --compressed_weights, use --weights instead
- Remove ModelInfo, replaced by ModelConfig.
Backprop:
- Reduce max loss, remove backward_scalar_test (timeout)
- Update thresholds because new RandInit changes rng eval order and thus numerics
PiperOrigin-RevId: 755317484