Add Bubble Tea TUI with interactive treemap

Cell canvas renderer with frame cache and a perceptual 256-colour
quantizer; responsive geometry (large/medium/small/too-small);
squarified treemap with nested previews, LOD grouping, category
colouring and adaptive labels; spatial arrow navigation with stable
NodeID selection; zoom and breadcrumbs; modal system (info, help,
confirm, save); list, file-type, top-N, scan-info, duplicate and
comparison views; live search/filter; mouse support; move-to-trash.

internal/app/app.go

@@ -36,6 +36,7 @@ type Config struct {
 	Theme        string
 	SizeMode     inventory.SizeMode
 	Mouse        bool
+	Color        string
 	Settings     config.Settings
 	Stdout       io.Writer
 	Stderr       io.Writer