"""
Grid Editor sub-package — FastAPI endpoints and helper functions.

Modules:
  - api          — barrel re-export (combined router + _build_grid_core)
  - api_grid     — build-grid, save-grid, get-grid endpoints
  - api_gutter   — gutter-repair endpoints
  - api_box      — build-box-grids endpoints
  - api_unified  — build-unified-grid endpoints
  - helpers      — barrel re-export of all helper symbols
  - columns      — column detection, cross-column splitting
  - filters      — word/zone filtering, border ghosts
  - headers      — header/heading detection, colspan detection
  - zones        — vertical dividers, zone splitting/merging
"""