feat: add the depletion meter

A discrete tick-strip rather than a smooth progress bar, borrowed from the
stamina meters these games all use — ticks read as a finite resource visibly
draining, which is the right metaphor for a limited-time event.

An event with no announced end gets a hatched strip, never a full meter.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

src/client/components/Meter.tsx

@@ -0,0 +1,65 @@
+import type { Urgency } from "../../shared/time.ts";
+
+const TICKS = 24;
+
+export const URGENCY_COLOR: Record<Urgency, string> = {
+  expired: "var(--color-faint)",
+  critical: "var(--color-critical)",
+  soon: "var(--color-soon)",
+  near: "var(--color-near)",
+  calm: "var(--color-calm)",
+};
+
+interface MeterProps {
+  /** 0–1 through the event's own window. Null when the end is unannounced. */
+  progress: number | null;
+  urgency: Urgency;
+  /** Suppresses the entry animation for long lists. */
+  animate?: boolean | undefined;
+  label: string;
+}
+
+/**
+ * The depletion meter — this interface's signature element.
+ *
+ * A discrete tick-strip rather than a smooth bar, borrowed from the stamina
+ * meters these games all use. Ticks read as a countable resource in a way a
+ * continuous bar does not, which is the right metaphor: what is left is
+ * finite and visibly draining.
+ *
+ * An event with no announced end gets a hatched strip instead of a filled one.
+ * It must not look like a full meter — "we don't know" and "loads of time" are
+ * different facts and conflating them is the failure this product avoids.
+ */
+export function Meter({ progress, urgency, animate = true, label }: MeterProps) {
+  const unknown = progress === null;
+  const remainingTicks = unknown
+    ? 0
+    : Math.max(0, Math.round((1 - progress) * TICKS));
+
+  return (
+    <div
+      className="meter"
+      role="img"
+      aria-label={label}
+      style={{ ["--tick" as string]: URGENCY_COLOR[urgency] }}
+    >
+      {Array.from({ length: TICKS }, (_, i) => {
+        // Ticks drain from the right, so the surviving run sits at the left
+        // edge and rows align into a readable ramp down the list.
+        const live = i < remainingTicks;
+        return (
+          <span
+            key={i}
+            className="meter-tick"
+            data-live={live}
+            data-unknown={unknown}
+            style={
+              animate ? { animationDelay: `${Math.min(i, 12) * 14}ms` } : undefined
+            }
+          />
+        );
+      })}
+    </div>
+  );
+}