perf: project-wide optimization pass + UI/theme fixes

Optimization (audited across src/, typecheck green):
- Crash guards: PurchaseAuction data?.result + stray text-node, AuctionItemDetail
  length>0, LiveAuction user?.contractorId, KYC params guard
- Hoisted render-defined components: Login MinimalInput (keyboard-focus bug),
  TenderFullDetail Section/InfoBox (subtree remount)
- Memoized hot paths: Spreadsheet ColumnHeaderRow/DataRow, list makeStyles,
  shared infinite-query select (stops per-render flatMap)
- Removed hot-path/in-list console logs; SkeletonList 10->1 shimmer

UI/theme: themed AppToast, redesigned sidebar drawer, list empty states,
KYC WebView cleanup

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/Spreadsheet/hooks/useGridTheme.ts

@@ -50,7 +50,7 @@ export const useGridTheme = (): GridTheme => {
       editorBg: colors.surface,
       editorBorder: colors.primary,
       searchHighlight: isDarkMode ? 'rgba(253,186,116,0.30)' : 'rgba(253,186,116,0.45)',
-      lockIcon: '#000000',
+      lockIcon: isDarkMode ? 'rgba(255,255,255,0.55)' : 'rgba(15,23,42,0.45)',
       primary: colors.primary,
       surface: colors.surface,
     }),