feat: Go to scopes are grouped like the Sources pane, an account at a time

The scope list follows the Sources pane: All, then each account (or
Databricks, or Repos) with its sources under it, in place of All Azure,
All Databricks and All repos. An account scope searches and loads only
that account. ctrl+s on a group header narrows to its group.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/ui/app/search_test.go

@@ -218,6 +218,31 @@ func TestSearchStartsWhereYouAre(t *testing.T) {
 	}
 }
 
+func TestSearchNarrowsToAccount(t *testing.T) {
+	t.Parallel()
+	d := newDriver(t)
+	d.keys("1", "g") // the first group header
+	header, _ := d.m.sources.Selected()
+	d.openSearch()
+	d.send(ctrl('s'))
+	v := d.m.search
+	if v.scope().id != accountScope+header.provider {
+		t.Fatalf("ctrl+s on %q narrowed to %q", header.label, v.scope().id)
+	}
+	if len(v.shown) == 0 || !strings.Contains(d.screen(), "Results in "+header.label) {
+		t.Errorf("no results in the account:\n%s", d.screen())
+	}
+	for _, o := range v.shown {
+		if providerOf(o.group) != header.provider {
+			t.Errorf("result from another account: %q", ansiStrip(o.label))
+		}
+	}
+	// The account's sources are under it, indented.
+	if next := v.scopes[v.src+1]; next.group == "" || providerOf(next.group) != header.provider || !strings.HasPrefix(ansiStrip(next.label), "  ") {
+		t.Errorf("after the account: %q", ansiStrip(next.label))
+	}
+}
+
 func TestSearchHint(t *testing.T) {
 	t.Parallel()
 	d := newDriver(t)