feat: replace compact player with draggable floating overlay

- Remove compact player mode (seekable bar inline was undifferentiated
  from standard; didn't have voice/chapter/warm-up controls)
- Add 'float' player style: a fixed, draggable mini-overlay positioned
  above the bottom mini-bar (bottom-right corner, z-55)
  · Seek bar, skip ±15/30s, play/pause, time, speed indicator
  · Drag handle (pointer capture) to reposition anywhere on screen
  · Animated playing pulse dot in the title row
  · Suppresses the standard non-idle inline block when active so
    there is no duplicate UI
- PlayerStyle type: 'standard' | 'float' (was 'compact')
- Bump localStorage key to reader_layout_v2 so old 'compact' pref
  does not pollute the new default
- Listening tab Style row now shows Standard / Float

ui/src/routes/books/[slug]/chapters/[n]/+page.svelte

@@ -52,7 +52,7 @@
 	type LineSpacing = 'compact' | 'normal' | 'relaxed';
 	type ReadWidth   = 'narrow' | 'normal' | 'wide';
 	type ParaStyle   = 'spaced' | 'indented';
-	type PlayerStyle = 'standard' | 'compact';
+	type PlayerStyle = 'standard' | 'float';
 	/** Controls how many lines fit on a page by adjusting the container height offset. */
 	type PageLines   = 'less' | 'normal' | 'more';
 
@@ -66,7 +66,7 @@
 		pageLines:   PageLines;
 	}
 
-	const LAYOUT_KEY = 'reader_layout_v1';
+	const LAYOUT_KEY = 'reader_layout_v2';
 	const LINE_HEIGHTS:    Record<LineSpacing, number> = { compact: 1.55, normal: 1.85, relaxed: 2.2 };
 	const READ_WIDTHS:     Record<ReadWidth,   string> = { narrow: '58ch', normal: '72ch', wide: 'min(90ch, 100%)' };
 	/**
@@ -950,7 +950,7 @@
 				<div class="flex items-center gap-3 px-3 py-2.5">
 					<span class="text-xs text-(--color-muted) w-14 shrink-0">Style</span>
 					<div class="flex gap-1.5 flex-1">
-						{#each ([['standard', 'Standard'], ['compact', 'Compact']] as const) as [s, lbl]}
+						{#each ([['standard', 'Standard'], ['float', 'Float']] as const) as [s, lbl]}
 							<button
 								type="button"
 								onclick={() => setLayout('playerStyle', s)}