What

PR #127 skips embossed text labels whose centre lands in a disabled partial-bin cell. _label_layout_cell in backend/app/services/stl_generator_manifold.py indexes rows with int(y_mm // GF_GRID) from the layout top, but shell geometry pitches rows from the bottom, placing the fractional remainder band at the top UI row. For fractional grid_y (e.g. 1.5) labels map to the wrong row: a disabled bottom row keeps a floating label (the #121 defect persists) and a disabled top row silently drops a valid label. Reproduced at STL level. X indexing is correct (fractional column is last in UI order).

Related cleanup: _make_text_labels gained an unused max_depth param, plus a hoist in generate_bin that exists only to pass it, leftover from a reverted clipping implementation.

Acceptance criteria

• _label_layout_cell indexes rows from the bottom (e.g. int((config.grid_y * GF_GRID - y_mm) // GF_GRID), clamped) so labels in fractional-grid bins map to the physically correct cell
• Test covering grid_y=1.5 with top and bottom rows disabled: label kept and skipped correctly in both cases
• Unused max_depth param and its generate_bin hoist removed
• Full backend suite passes