Redesign dashboard/screener UI for improved density and performance

- Add compact/dense CSS tokens for tighter layouts
- Add size prop to Button (default/compact) and Input (default/compact)
- Add density prop to Panel (normal/compact/dense)
- Add size prop to MetricCard (default/compact/inline)
- Create IndexCardRow component for horizontal metric display
- Create FilterChip component for removable filter tags
- Redesign Command Center with flat sections, reduced cards
- Tighten AppShell spacing (sidebar w-56, header mb-3, main space-y-4)

Design goals achieved:
- Denser, cleaner terminal-style layout
- Reduced card usage in favor of flat sections with dividers
- More space-efficient controls and metrics
- Better use of widescreen layouts

components/dashboard/index-card-row.tsx

@@ -0,0 +1,45 @@
+"use client";
+
+import { memo } from "react";
+import { cn } from "@/lib/utils";
+
+type IndexCardProps = {
+  label: string;
+  value: string;
+  delta?: string;
+  positive?: boolean;
+};
+
+type IndexCardRowProps = {
+  cards: IndexCardProps[];
+  className?: string;
+};
+
+const IndexCard = memo(function IndexCard({
+  label,
+  value,
+  delta,
+  positive = true,
+}: IndexCardProps) {
+  return (
+    <div className="index-card">
+      <p className="label">{label}</p>
+      <p className="value">{value}</p>
+      {delta ? (
+        <p className={cn("delta", positive ? "positive" : "negative")}>
+          {delta}
+        </p>
+      ) : null}
+    </div>
+  );
+});
+
+export function IndexCardRow({ cards, className }: IndexCardRowProps) {
+  return (
+    <div className={cn("index-card-row", className)}>
+      {cards.map((card, index) => (
+        <IndexCard key={`${card.label}-${index}`} {...card} />
+      ))}
+    </div>
+  );
+}