Stage 7 polish (round 3): zoom magnifies labels, popover edge-anchor, flash x2

- item 5: move container-type to the zoom-scaled .scaler so cqw labels grow WITH the board (magnifying-glass zoom); new e2e measures the font grows ~1.85x
- item 8: confirm popovers anchor to the trigger's right edge (no longer run off-screen)
- item 9: last-word flash runs 2 cycles then settles to normal (was infinite)

ui/src/components/HoldConfirm.svelte

@@ -92,8 +92,7 @@
   .popover {
     position: absolute;
     bottom: calc(100% + 6px);
-    left: 50%;
-    transform: translateX(-50%);
+    right: 0;
     z-index: 19;
     display: flex;
     flex-direction: column;