feat(webui): sparkline, capacity meter, metric tile components

webui/src/lib/components/CapacityMeter.svelte

@@ -0,0 +1,30 @@
+<script>
+  let { depth = 0, cap = 1, segments = 8, label = "capacity" } = $props();
+
+  const ratio = $derived(cap > 0 ? Math.min(depth / cap, 1) : 0);
+  const lit = $derived(Math.round(ratio * segments));
+  const nearFull = $derived(ratio > 0.9);
+  const barColor = $derived(nearFull ? "var(--danger)" : "var(--signal)");
+</script>
+
+<div class="meter" role="meter" aria-label={label} aria-valuemin={0} aria-valuemax={cap} aria-valuenow={depth}>
+  {#each Array(segments) as _, i}
+    <span class="seg" class:lit={i < lit} style:--seg-color={barColor}></span>
+  {/each}
+</div>
+
+<style>
+  .meter { display: flex; gap: 3px; align-items: stretch; height: 100%; }
+  .seg {
+    flex: 1;
+    min-width: 4px;
+    border-radius: 2px;
+    background: var(--panel-2);
+    border: 1px solid var(--line);
+    transition: background .2s, border-color .2s;
+  }
+  .seg.lit {
+    background: var(--seg-color);
+    border-color: var(--seg-color);
+  }
+</style>

webui/src/lib/components/MetricTile.svelte

@@ -0,0 +1,23 @@
+<script>
+  import Sparkline from "./Sparkline.svelte";
+
+  let { label = "", value = "", sub = "", sparkValues = [], sparkColor = undefined } = $props();
+</script>
+
+<div class="tile panel">
+  <span class="label-caps">{label}</span>
+  <span class="value mono">{value}</span>
+  {#if sub}<span class="sub">{sub}</span>{/if}
+  {#if sparkValues.length > 0}
+    <div class="spark">
+      <Sparkline values={sparkValues} color={sparkColor ?? "var(--signal)"} />
+    </div>
+  {/if}
+</div>
+
+<style>
+  .tile { display: flex; flex-direction: column; gap: 6px; padding: 14px 16px; }
+  .value { font-size: 26px; font-weight: 700; line-height: 1.1; color: var(--text); }
+  .sub { font-size: 11px; color: var(--muted); }
+  .spark { height: 28px; margin-top: 4px; }
+</style>

webui/src/lib/components/Sparkline.svelte

@@ -0,0 +1,48 @@
+<script>
+  let { values = [], color = "var(--signal)" } = $props();
+
+  const W = 100;
+  const H = 28;
+  const PAD = 2;
+
+  const points = $derived.by(() => {
+    if (!values || values.length === 0) return "";
+    if (values.length === 1) {
+      const y = H / 2;
+      return `${PAD},${y} ${W - PAD},${y}`;
+    }
+    let min = values[0];
+    let max = values[0];
+    for (let i = 1; i < values.length; i++) {
+      if (values[i] < min) min = values[i];
+      if (values[i] > max) max = values[i];
+    }
+    const range = max - min || 1;
+    const step = (W - PAD * 2) / (values.length - 1);
+    return values
+      .map((v, i) => {
+        const x = PAD + i * step;
+        const y = H - PAD - ((v - min) / range) * (H - PAD * 2);
+        return `${x.toFixed(2)},${y.toFixed(2)}`;
+      })
+      .join(" ");
+  });
+</script>
+
+{#if points}
+  <svg class="sparkline" viewBox="0 0 {W} {H}" preserveAspectRatio="none" aria-hidden="true">
+    <polyline
+      points={points}
+      fill="none"
+      stroke={color}
+      stroke-width="1.5"
+      stroke-linecap="round"
+      stroke-linejoin="round"
+      vector-effect="non-scaling-stroke"
+    />
+  </svg>
+{/if}
+
+<style>
+  .sparkline { display: block; width: 100%; height: 100%; }
+</style>