formats: a scale-0 leaf must not claim the draw and blank its parent

Found by inspection while the disc tests ran. The leaf branch set its
something-was-drawn flag unconditionally after calling blit, but blit returns
early on a zero scale -- collapsed to nothing, not unset. So a scale-0 leaf would
have been counted as drawn, its parent skipped, and the element blanked outright.

pgloading_loop5 s leaf is scale (0,0), so this was live on all four loading
screens, and scale-0 is one of the failures this corpus is already named for.
Fixed by skipping a zero-scale leaf pose before it can claim the draw; the
loading builds render afterwards at 4.0 percent non-black.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd

crates/sylpheed-formats/src/ui_layout.rs

@@ -1158,6 +1158,15 @@ pub fn compose_with_order(
                 let lsp = le.sprite.clone().unwrap_or_else(|| le.name.clone());
                 let Some(&(so, ss)) = build.sprites.get(&lsp) else { continue };
                 let Some(limg) = t8ad::parse(&bundle[so..so + ss]) else { continue };
+                // 🔴 Only count it as drawn if it CAN draw. `blit` returns early
+                // on a zero scale — "collapsed to nothing", not "unset" — so
+                // setting the flag unconditionally would let a scale-0 leaf
+                // suppress its parent and blank the element outright.
+                // `pgloading_loop5`'s leaf is scale (0,0), and scale-0 is one of
+                // the failures this corpus is already named for.
+                if lk.scale_x == 0 || lk.scale_y == 0 {
+                    continue;
+                }
                 blit(&mut canvas, w, h, &limg, &lk, le.pivot_x, le.pivot_y);
                 any = true;
             }