[PTO] Add TileBufArray type and array-style dynamic indexing

[TaoTao-real]

Summary

• add new IR type !pto.tile_buf_array<N x !pto.tile_buf<...>>
• add container ops pto.make_tile_buf_array and pto.tile_buf_array_get
• add verifiers for array construction/get semantics
• add C API + Python bindings for TileBufArrayType
• add Python ergonomic helpers: TileBufArray, make_tile_buf_array, tile_buf_array_get
• add PTOViewToMemref lowering for tile_buf_array_get:
  • constant index: direct replacement
  • dynamic index: lower to scf.if ladder over element choices (MVP: direct no-result users)
• add sample test/samples/TileBufArray/tile_buf_array_basic.py

Why

This introduces a first-class way to represent an array of homogeneous tile buffers with dynamic indexing while allowing non-contiguous physical addresses.

Validation

• python3 -m py_compile python/pto/dialects/pto.py test/samples/TileBufArray/tile_buf_array_basic.py ✅
• git diff --check ✅

Notes

• scope is TileBufArray only; no InsertSync/A5 sync behavior changes.