refactor: move NTP config to separate NonuniformTPConfig class

- Create NonuniformTPConfig dataclass in nonuniform_tp.py
- Remove NTP fields from DistributedDataParallelConfig (non-intrusive)
- Update all NTP functions/classes to use NonuniformTPConfig
- Update all tests to use NonuniformTPConfig
- Update CLAUDE.md documentation

This makes the NTP implementation completely self-contained with
zero modifications to core Megatron files.

Author: daiyaanarfeen

megatron/core/distributed/distributed_data_parallel_config.py

@@ -162,28 +162,6 @@ class DistributedDataParallelConfig:
     delay_wgrad_compute: bool = False
     """Delay the weight gradient computation to improve batch-level communication overlapping"""
 
-    tp_base: int = 8
-    """Base for tensor parallelism. This is the number of ranks in healthy tensor parallel groups.
-       Used for nonuniform tensor parallelism."""
-
-    tp_spares: int = 0
-    """Number of spares for nonuniform tensor parallelism. When > 0, enables nonuniform TP mode
-       where (tp_base - tp_spares) ranks handle computation and tp_spares ranks provide fault tolerance."""
-
-    num_reduced_tp_dp_ranks: int = 1
-    """Number of DP ranks that use reduced TP (tp_base - tp_spares). The remaining DP ranks use
-       full tp_base. Reduced TP ranks are assumed to come first in the global rank ordering."""
-
-    non_active_ranks_per_dp: Optional[Dict[Tuple[int, int, int], List[int]]] = None
-    """Mapping of (DP rank, CP rank, PP rank) to list of non-active (spare) local TP rank IDs.
-       This allows specifying arbitrary GPU failures across all parallelism dimensions.
-       Example: {(0,0,0): [0,3], (0,1,0): [1,2], (1,0,0): [0,3]} means:
-         - DP rank 0, CP rank 0, PP rank 0 has local TP ranks 0,3 as spares
-         - DP rank 0, CP rank 1, PP rank 0 has local TP ranks 1,2 as spares
-         - DP rank 1, CP rank 0, PP rank 0 has local TP ranks 0,3 as spares
-       The number of non-active ranks must be consistent across CP replicas within each DP rank.
-       If None, defaults to last tp_spares ranks as non-active."""
-
     def __post_init__(self):
         import os