refactor(pt): fully refactor of HybridMuon optimizer (#5275)

1. refactor name-based routing
2. add slice mode for HybridMuon opt
3. add Magma-lite damping for Muon path

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## Summary by CodeRabbit

* **New Features**
* HybridMuon gains routing modes (slice, 2d, flat), name-aware routing
for biases/Adam variants, and a magma_muon option for Magma-lite
damping. Optimizer now accepts named parameters; deprecated 2D-only
options removed.

* **Documentation**
* Updated optimizer docs to describe new routing modes, magma_muon and
flash_muon options, and adjusted lr_adjust default.

* **Tests**
* Expanded tests for routing modes, Magma damping, and state
compatibility; some legacy tests consolidated.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: OutisLi