v0.6.37 — two bugs nailed by the v0.6.36 trace

Bugs fixed (both diagnosed from the v0.6.36 diagnostic log)

1. Cells stacked at spawn instead of laid out

The trace showed every new cell spawning at the master's left-edge position (e.g. 92,1311) with NO LAYOUT_RUN between cells. Only after some unrelated event triggered the next repack did all the stacked cells snap into honeycomb slots at once — what you saw as "started off spaced out".

Fix: forest_controller._spawn_item now calls the master's layout function after each cell is added, so every new cell lands on its slot as it appears.

2. Master snapping to its own descendants

25+ SNAP_COMMIT events in the trace had the forest snapping to one of its own children. When the forest is dragged, the children move with it (the GROUP_MOVE cascade), and the snap engine saw them as nearby snap targets — offering the forest a slot relative to its own children. That's the "highlighted docking is misaligned with the forest" symptom.

Fix: SnapEngine._tick now excludes the dragged source's descendants (recursive through any nested masters) from candidate snap targets.

3. Icons / overlay oversized — instrumentation added

No root cause from the v0.6.36 trace (SNAPSHOT showed all cells at size_px=56). Extended the SNAPSHOT to log widget_w/h + icon_scale per cell, so the next time it happens the trace will show whether logical size and rendered size diverge.

Tests

1741 passed.