feat(frontend): add ProgressRing component — SVG progress arc with percentage label

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/components/ProgressRing.svelte

@@ -0,0 +1,26 @@
+<script lang="ts">
+let { percentage }: { percentage: number } = $props();
+</script>
+
+<div class="flex flex-col items-center">
+	<svg width="36" height="36" viewBox="0 0 20 20">
+		<circle cx="10" cy="10" r="7" fill="none" stroke="var(--c-line)" stroke-width="2" />
+		<circle
+			class="fill-arc"
+			cx="10"
+			cy="10"
+			r="7"
+			fill="none"
+			stroke="var(--c-accent)"
+			stroke-width="2"
+			stroke-linecap="round"
+			transform="rotate(-90 10 10)"
+			stroke-dasharray="{(percentage / 100) * 43.98} 43.98"
+		/>
+	</svg>
+	<span
+		class="block text-center font-sans text-[10px] font-bold {percentage > 0 ? 'text-accent' : 'text-gray-400'}"
+	>
+		{percentage}%
+	</span>
+</div>