feat: add landing page and complete app

- EreaderMockup: animated SVG e-reader illustration
- DitherComparison: interactive before/after demo
- Landing page with hero, features, about sections
- Converter with view mode toggle and batch download
- Updated exports and theme styles

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/lib/components/EreaderMockup.svelte

@@ -0,0 +1,121 @@
+<script lang="ts">
+	interface Props {
+		class?: string;
+	}
+
+	let { class: className = '' }: Props = $props();
+</script>
+
+<svg
+	viewBox="-30 -20 340 440"
+	fill="none"
+	xmlns="http://www.w3.org/2000/svg"
+	class={className}
+	style="overflow: visible;"
+>
+	<!-- Device body with shadow -->
+	<defs>
+		<filter id="deviceShadow" x="-50%" y="-50%" width="200%" height="200%">
+			<feDropShadow dx="4" dy="12" stdDeviation="16" flood-color="#000" flood-opacity="0.25" />
+		</filter>
+		<linearGradient id="screenGradient" x1="0%" y1="0%" x2="0%" y2="100%">
+			<stop offset="0%" stop-color="#f8f8f8" />
+			<stop offset="100%" stop-color="#e8e8e8" />
+		</linearGradient>
+		<clipPath id="screenClip">
+			<rect x="24" y="24" width="232" height="310" rx="2" />
+		</clipPath>
+	</defs>
+
+	<!-- Device outer shell -->
+	<rect
+		x="4"
+		y="4"
+		width="272"
+		height="372"
+		rx="16"
+		fill="#2a2a2a"
+		filter="url(#deviceShadow)"
+	/>
+
+	<!-- Device bezel -->
+	<rect
+		x="8"
+		y="8"
+		width="264"
+		height="364"
+		rx="12"
+		fill="#1a1a1a"
+	/>
+
+	<!-- Screen area -->
+	<rect
+		x="24"
+		y="24"
+		width="232"
+		height="310"
+		rx="2"
+		fill="url(#screenGradient)"
+	/>
+
+	<!-- Sample e-ink image (abstract landscape) -->
+	<g clip-path="url(#screenClip)">
+		<!-- Sky gradient -->
+		<rect x="24" y="24" width="232" height="155" fill="#d4d4d4" />
+
+		<!-- Sun/moon (behind mountains) -->
+		<circle cx="200" cy="70" r="25" fill="#f0f0f0" />
+
+		<!-- Mountains - back layer -->
+		<path
+			d="M24 160 L80 100 L140 140 L200 80 L256 130 L256 334 L24 334 Z"
+			fill="#a0a0a0"
+		/>
+
+		<!-- Mountains - front layer -->
+		<path
+			d="M24 180 L60 130 L120 170 L180 120 L240 160 L256 150 L256 334 L24 334 Z"
+			fill="#707070"
+		/>
+
+		<!-- Hills/foreground -->
+		<path
+			d="M24 200 Q80 180 140 210 Q200 240 256 200 L256 334 L24 334 Z"
+			fill="#505050"
+		/>
+
+		<!-- Trees silhouette -->
+		<g fill="#404040">
+			<path d="M40 210 L50 180 L60 210 Z" />
+			<path d="M55 215 L65 190 L75 215 Z" />
+			<path d="M200 225 L212 195 L224 225 Z" />
+			<path d="M215 230 L225 205 L235 230 Z" />
+		</g>
+
+		<!-- Subtle dither pattern overlay -->
+		<g opacity="0.08">
+			{#each Array(50) as _, i}
+				{#each Array(65) as _, j}
+					{#if (i + j) % 2 === 0}
+						<rect x={24 + j * 3.6} y={24 + i * 6.2} width="1" height="1" fill="#000" />
+					{/if}
+				{/each}
+			{/each}
+		</g>
+	</g>
+
+	<!-- Screen bezel inner edge highlight -->
+	<rect
+		x="24"
+		y="24"
+		width="232"
+		height="310"
+		rx="2"
+		fill="none"
+		stroke="#333"
+		stroke-width="1"
+	/>
+
+	<!-- Home button / indicator -->
+	<circle cx="140" cy="356" r="8" fill="#333" stroke="#444" stroke-width="1" />
+</svg>