feat: add Mano manifold optimizer (mano_adamw)

- implement Mano (v2) with axis-rotating tangent projection and manifold normalization, replacing Newton-Schulz iteration
- composite ManoAdamW reuses partition_optimizer_parameters and composite helpers
- register mano_adamw in OptimizerFactory, export Mano and ManoAdamW
- add --mano_momentum and --mano_nesterov CLI options in Optimizer group
- add mano_adamw hyperparameters branch in train.py
- document mano_adamw in params.md
- add tests for single-step projection, axis alternation, factory registration, closure, and resume

tests/optim/test_nora_nadamw.py

@@ -148,7 +148,11 @@ def test_parameter_partition_covers_all_model_structures(model_overrides):
 
 
 def test_factory_registers_nora_default_and_legacy_muon():
-    assert OptimizerFactory.list_registered() == ["muon_adamw", "nora_nadamw"]
+    assert OptimizerFactory.list_registered() == [
+        "mano_adamw",
+        "muon_adamw",
+        "nora_nadamw",
+    ]
     model = AutoRegressiveLM(make_tiny_config())
     optimizer = OptimizerFactory.create("nora_nadamw", model, lr=3e-4)
     assert isinstance(optimizer, NoraNAdamW)