feat(stark): unified-domain LDE for shared FRI across different table sizes

Extend all tables' trace and composition polynomial LDE evaluations to
the largest LDE domain (max_lde_size) so shared FRI can query all tables
at the same coset points without per-table index mapping.

Key changes:
- Add `extend_pool_columns_to_size` helper: extends LDE columns from
  their natural size to a target size via iFFT(coset) + zero-pad + FFT(coset)
- Phase A/C commits: extend main/aux LDE columns to max_lde_size before
  building Merkle trees, so all trees share the same height
- Round 2 composition poly: extend H0/H1 part evaluations to max_lde_size
  before committing, matching the unified domain
- Round 4 openings: reconstruct extended LDE for opening at shared query
  indices (no iota>>shift mapping needed)
- Remove `all_same_domain` guard and per-table FRI fallback -- the shared
  FRI path now handles all multi-table proves uniformly
- Verifier: use unified max-domain evaluation points for DEEP reconstruction
  and Merkle proof verification (no per-table index mapping)
- Fix stride calculations in Round 3 OOD eval and DEEP composition to
  handle extended composition poly evaluations correctly

Author: diegokingston