Fuse RoPE across MLite attention implementations

[ISEEKYAN]

Summary

• add a single MLite kernel boundary for TE-backed generic and MLA fused RoPE providers
• route dense/MRoPE, MLA, DSA, and CSA RoPE sites through the fused path while preserving the unfused reference path
• enable RoPE fusion by default in the relevant typed implementation configs
• add adapter, routing, runtime-config, and AST layering contract coverage

Validation

• focused CPU suite: 43 passed
• ruff and diff checks passed
• eos Slurm 5538097: COMPLETED 0:0, 5 passed, 0 skipped (forward and backward coverage)