feat(layout): add YaziPaneRow 3-pane layout primitive

Add the shared parent | current | preview row primitive that implements
yazi's mgr.ratio = [1, 3, 3] contract via Yoga flexGrow, so every list
tab renders an identical, layout-stable shell regardless of terminal
size.

- New YaziPaneRow component: three bordered columns grow at 1/7 : 3/7
  : 3/7 with flexBasis=0 (content can never stretch its slot). The
  current column carries the accent focus ring when `focused` is
  truthy; parent and preview stay muted. The blank parent keeps its
  1/7 slot with a muted placeholder rather than collapsing.
- PANE_RATIO.current 4 -> 3 to match yazi's [1, 3, 3].
- Add render-based tests covering the 1:3:3 ratios (incl. null
  parent/preview) and the focused/unfocused accent ring behavior.
- Configure the bun test preload for the solid JSX transform.

src/utils/navigation.ts

@@ -66,13 +66,13 @@ export const LayerDepths = {
 	[TABS.SETTINGS]: SettingsPaneCount,
 };
 
-// Yazi-style pane grow ratios (parent : current : preview) ≈ [1, 4, 3].
+// Yazi-style pane grow ratios (parent : current : preview) = [1, 3, 3].
 // Panes use flexGrow (Yoga) so columns always sum to the row width regardless
 // of terminal size — more robust than fixed percentages and exactly mirrors
 // yazi's `mgr.ratio` config. Set a slot's ratio to 0 to hide it (2-pane tabs).
 export const PANE_RATIO = {
 	parent: 1,
-	current: 4,
+	current: 3,
 	preview: 3,
 } as const;