fix: per-segment bg coloring for full-screen cream + warm cursor highlight

Previous approach using Place() for full-screen bg and WarmRowStyle wrapper
failed because inner ANSI resets (\x1b[m) kill outer Background() styles.

New approach: every styled segment carries its own Background() via theme.Bg()
and theme.WBg() helpers. Per-line Place() fills trailing whitespace. This
ensures cream bg (#fdf6ef) on every pixel of every line, and warm bg (#f8f0e6)
consistently across the cursor row.

Also fixes bottom bar overflow on narrow terminals with adaptive keybindings.

cli/internal/update/update.go

@@ -14,7 +14,7 @@ import (
 
 const (
 	// CurrentVersion is the embedded build version. Updated at release time.
-	CurrentVersion = "0.1.2"
+	CurrentVersion = "0.1.3"
 
 	repoOwner = "noauf"
 	repoName  = "Transmute"