refactor: codebase opschoning — type safety, error handling, central config, page splits

- categorie A: alle catch(e: any) → catch(e: unknown) met instanceof check
- categorie B: stille .catch() logging toegevoegd (SWRegister, admin, upload, auth)
- categorie C: hardcoded 192.168.1.176 IPs vervangen door env var defaults
- categorie D: page files >250L gesplitst (history, settings, explorer, admin/payment,
  ipns, users, upload, dashboard) in helpers/components
- categorie E: eslint-disable vervangen in SearchInput.tsx
- src/lib/config.ts centrale config module (localhost defaults)
- CSP in next.config.ts dynamisch via env var
- deploy.sh: geen hardcoded IP meer (REQUIRED arg)
- lib/api/ lib/auth/ lib/wallet/ lib/search-index/ lib/storage/ gesplitst in modules
- ongebruikte bestanden verwijderd: api.ts, auth.tsx, wallet.ts, search-index.ts,
  PaymentPanel.tsx, SearchBar.tsx, proxy.ts, serve-static.js

src/app/layout-portal.tsx

@@ -3,12 +3,20 @@
 import PortalSidebar from '@/components/PortalSidebar';
 import PortalHeader from '@/components/PortalHeader';
 
-export default function PortalLayout({ children }: { children: React.ReactNode }) {
+interface PortalLayoutProps {
+  children: React.ReactNode;
+  /** Optional custom header. Defaults to <PortalHeader /> if omitted. */
+  header?: React.ReactNode;
+  /** Optional custom sidebar. Defaults to <PortalSidebar /> if omitted. */
+  sidebar?: React.ReactNode;
+}
+
+export default function PortalLayout({ children, header, sidebar }: PortalLayoutProps) {
   return (
     <div className="flex min-h-screen">
-      <PortalSidebar />
+      {sidebar ?? <PortalSidebar />}
       <div className="flex-1 flex flex-col ml-56">
-        <PortalHeader />
+        {header ?? <PortalHeader />}
         <main className="flex-1 p-6">{children}</main>
       </div>
     </div>