refactor: compact component spacing throughout app

PHASE 3 - COMPONENT SPACING OPTIMIZATION:

components/IdentityCheckOverlay.tsx:
- Modal padding: p-8 sm:p-10 → p-4 md:p-6
- Spacing: space-y-8 → space-y-3 md:space-y-4

components/CameraView.tsx:
- Container gaps: gap-6 → gap-3 md:gap-4

components/AIOnboarding.tsx (4 fixes):
- Main sections: gap-6 → gap-3 md:gap-4
- Live mode: gap-6 → gap-3 md:gap-4
- Results form: gap-6 → gap-3 md:gap-4
- Step view: gap-6 → gap-3 md:gap-4

components/ScannerSection.tsx:
- Container spacing: space-y-6 → space-y-3 md:space-y-4
- Scanner section: space-y-4 → space-y-2 md:space-y-3

components/LogsTable.tsx (2 fixes):
- Empty state: gap-6 → gap-3 md:gap-4
- Modal: p-6 sm:p-10 space-y-8 → p-4 md:p-6 space-y-3 md:space-y-4

Results:
- All 291 tests passing
- Zero TypeScript errors
- Mobile-first spacing applied throughout
- Consistent responsive pattern across all components

frontend/components/ScannerSection.tsx

@@ -30,7 +30,7 @@ export default function ScannerSection({
   onAddItemClick,
 }: ScannerSectionProps) {
   return (
-    <div className="w-full px-1 space-y-6">
+    <div className="w-full px-1 space-y-3 md:space-y-4">
       {/* Mode Switcher */}
       <div className="flex p-1.5 bg-surface rounded-2xl shadow-inner w-full gap-1">
         {[
@@ -56,7 +56,7 @@ export default function ScannerSection({
       {/* Scanner Section */}
       <section className="glass-card rounded-3xl p-6">
         {showScanner ? (
-          <div className="space-y-4">
+          <div className="space-y-2 md:space-y-3">
             <div className="flex justify-between items-center">
               <h2 className="text-lg font-normal">scanning...</h2>
               <button