feat: add Storybook component explorer

src/lib/ui/components/Button.svelte

@@ -0,0 +1,80 @@
+<script lang="ts">
+  import IconGlyph from "./IconGlyph.svelte";
+
+  let {
+    label,
+    variant = "primary",
+    size = "default",
+    icon,
+    disabled = false,
+    loading = false,
+    type = "button",
+  }: {
+    label: string;
+    variant?: "primary" | "secondary" | "danger" | "ghost";
+    size?: "default" | "compact";
+    icon?: string;
+    disabled?: boolean;
+    loading?: boolean;
+    type?: "button" | "submit" | "reset";
+  } = $props();
+</script>
+
+<button
+  class="ui-button"
+  data-variant={variant}
+  data-size={size}
+  data-loading={loading}
+  {disabled}
+  {type}
+>
+  {#if icon}
+    <IconGlyph name={icon} size="sm" />
+  {/if}
+  <span>{loading ? "Loading" : label}</span>
+</button>
+
+<style>
+  .ui-button {
+    display: inline-grid;
+    grid-auto-flow: column;
+    gap: var(--ui-space-2);
+    align-items: center;
+    justify-content: center;
+    min-height: 2.5rem;
+    border: var(--ui-border);
+    background: var(--ui-color-accent);
+    color: var(--ui-color-canvas);
+    cursor: pointer;
+    font-size: 0.76rem;
+    font-weight: 850;
+    letter-spacing: 0;
+    padding: 0 var(--ui-space-4);
+    text-transform: uppercase;
+  }
+
+  .ui-button[data-size="compact"] {
+    min-height: 2rem;
+    padding-inline: var(--ui-space-3);
+  }
+
+  .ui-button[data-variant="secondary"] {
+    background: var(--ui-color-surface-raised);
+    color: var(--ui-color-text);
+  }
+
+  .ui-button[data-variant="danger"] {
+    background: var(--ui-color-danger);
+    color: var(--ui-color-text);
+  }
+
+  .ui-button[data-variant="ghost"] {
+    background: transparent;
+    color: var(--ui-color-muted);
+  }
+
+  .ui-button:disabled {
+    cursor: not-allowed;
+    opacity: 0.48;
+  }
+</style>