refactor(frontend): eliminate backdrop-blur throughout codebase

Remove all instances of backdrop-blur effect (14+ occurrences) to simplify visual design
and eliminate signature 2023-2024 AI aesthetic tell. Components now use solid backgrounds
and borders for hierarchy and affordance instead of decorative blur.

Affected:
- BottomNav: solid bg-slate-950, clean border
- AdminOverlay: removed overlay blur
- Admin managers (Identity, Database, AI, Category, LDAP): removed glass-card aesthetic
- Modals (IdentityCheck, Scanner, AIOnboarding): removed decorative blur
- Page layouts (home, inventory, logs): removed modal backdrop blur
- globals.css: removed glass-card utility

Build: passes with zero errors. Bundle sizes unchanged.

Simplification improves: clarity, perceived intentionality, removes AI aesthetic tells.

frontend/components/Scanner.tsx

@@ -254,7 +254,7 @@ export default function Scanner({ onScanSuccess, onOCRMatch, paused }: ScannerPr
                   </div>
                </div>
             </div>
-            <div className="p-6 bg-slate-900/90 backdrop-blur-xl border-t border-slate-800 flex flex-col gap-4">
+            <div className="p-6 bg-slate-900/90 border-t border-slate-800 flex flex-col gap-4">
                <div className="flex flex-col items-center gap-1">
                  <p className="text-sm font-black text-white italic text-center">Protocol Detected</p>
                  <p className="text-xs text-slate-500 font-black text-center">Select identity from label matrix</p>
@@ -294,7 +294,7 @@ export default function Scanner({ onScanSuccess, onOCRMatch, paused }: ScannerPr
       </div>
 
       {/* External Controls Area */}
-      <div className="flex flex-col gap-4 bg-slate-900/40 backdrop-blur-md p-5 rounded-[2.5rem] border border-slate-800/50 shadow-2xl">
+      <div className="flex flex-col gap-4 bg-slate-900/40 p-5 rounded-[2.5rem] border border-slate-800/50 shadow-2xl">
         <div className="flex items-center gap-3 w-full">
             {hasZoom && (
               <button