refactor: flatten Financials page UI for improved density

- Move Matrix panel to top position for better visibility
- Hide trend chart by default (showTrendChart: false)
- Flatten panel design by removing titles and borders
- Compact spacing and reduce UI chrome throughout
- Add chart toggle button in toolbar
- Enable dense and virtualized modes on StatementMatrix
- Fix missing useState import in FinancialsToolbar

The creates a cleaner, more professional Bloomberg terminal-style
interface with better information density and
improved performance through virtualization for large datasets.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

app/financials/page.tsx

@@ -888,7 +888,7 @@ function FinancialsPageContent() {
         </div>
       </Panel>
 
-      <Panel title="Trend Chart" subtitle="Default trend series for the selected surface." variant="surface">
+      <Panel>
         {loading ? (
           <p className="text-sm text-[color:var(--terminal-muted)]">Loading trend chart...</p>
         ) : chartData.length === 0 || trendSeries.length === 0 ? (
@@ -1064,7 +1064,7 @@ function FinancialsPageContent() {
           renderDimensionValue={renderDimensionValue}
         />
       ) : (
-        <Panel title="Row Details" subtitle="Inspect provenance, formulas, and dimensional evidence for the selected row." variant="surface">
+        <Panel>
           {!selectedRow ? (
             <p className="text-sm text-[color:var(--terminal-muted)]">Select a row to inspect details.</p>
           ) : (
@@ -1149,7 +1149,7 @@ function FinancialsPageContent() {
       )}
 
       {(surfaceKind === 'income_statement' || surfaceKind === 'balance_sheet' || surfaceKind === 'cash_flow_statement') && financials ? (
-        <Panel title="Metric Validation" subtitle="Validation remains limited to statement-derived taxonomy metrics in v1." variant="surface">
+        <Panel>
           <div className="mb-3 flex items-center gap-2 text-sm text-[color:var(--terminal-muted)]">
             <AlertTriangle className="size-4" />
             <span>Overall status: {financials.metrics.validation?.status ?? 'not_run'}</span>