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/ui/filter-chip.tsx

@@ -0,0 +1,26 @@
+"use client";
+
+import { X } from "lucide-react";
+import { cn } from "@/lib/utils";
+
+type FilterChipProps = {
+  label: string;
+  onRemove: () => void;
+  className?: string;
+};
+
+export function FilterChip({ label, onRemove, className }: FilterChipProps) {
+  return (
+    <span className={cn("filter-chip", className)}>
+      <span className="truncate">{label}</span>
+      <button
+        type="button"
+        onClick={onRemove}
+        className="remove"
+        aria-label={`Remove ${label} filter`}
+      >
+        <X className="size-3" />
+      </button>
+    </span>
+  );
+}