[vaprdev]

Summary

In character mode each cell shows only two colors, so fine fronds, corn and raked gravel broke into speckle that shimmered as it moved, and quadrant terminals flickered. Scenes now know when they draw for terminal cells and draw bolder there.

-resize(W, H)
+resize(W, H, cells?)          set when each pixel is a sub-pixel of a terminal cell
 Canvas
+  this.cells
+  thick(radius, min)          stroke radius that never drops below min on cells
+  blade(spine, widths, color) a frond's leaflets as one scalloped blade
 engine.tsx                    steadier quadrant cell fitting
 beach, farm, jungle, ocean, prehistoric, zen   bolder detail on cells

Snaps and pixel mode are unchanged. Fronds and corn stay near-silhouettes under rim light on cells. Documented in CONTRIBUTING.

Evidence

Terminal previews, before (main) on the left, after on the right; the last row is quadrant mode.

Verification: bun run typecheck passes; CI's check job runs dev/check.ts (flicker, errors) on this branch; quadrant mode (WALLPAPER_OCTANTS=0) is checked on the integration branch in #1.

Merge Danger

Door: two-way

Blast Radius: engine

Touches the cell-fitting path in src/engine.tsx for every wallpaper; Scene.resize gains an optional argument, so existing scenes keep working.

Merged together with the other visual improvements in #1; this PR's CI screenshot check fails by design because screenshots are regenerated there.