Chart builder: discoverable entry points — Build Chart door, dataset picker, no-datasets state

src/app/components/ChartBuilderModal.module.css

@@ -13,10 +13,28 @@
   min-width: 0;
 }
 
-.muted {
+/* ── No-dataset states: Carbon no-data empty state / dataset chooser ──── */
+
+.emptyState {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+  gap: var(--space-4);
+  max-width: 48ch;
+  padding: var(--space-7) var(--space-6);
+}
+
+.emptyTitle {
+  margin: 0;
+  font-size: 16px;
+  font-weight: 600;
+  color: var(--text);
+}
+
+.emptyBody {
   margin: 0;
-  padding: var(--space-5);
   font-size: 14px;
+  line-height: 1.5;
   color: var(--text-secondary);
 }
 
@@ -33,14 +51,11 @@
   min-height: 0;
 }
 
-.datasetName {
-  margin: 0;
-  font-size: 13px;
-  color: var(--text-secondary);
-}
-
-.datasetName strong {
-  color: var(--text);
+/* The dataset picker pinned at the top of the config pane. */
+.datasetRow {
+  display: flex;
+  align-items: center;
+  gap: var(--space-3);
 }
 
 /* ── Data section: filters, calculated fields, row preview (spec §06 → Data) ──── */