feat: SIWE auth, auto-pin, pin search/share, explorer improvements

- SIWE server-side auth (siwe + jose JWT)
- Wallet provider fallback (MAOS -> MetaMask)
- Auto-pin after upload (quick + crypto)
- Pin search/filter in explorer
- Share button (gateway link) per pin
- Copy CID button per pin
- Breadcrumb root navigation fix
- Hydration mismatch fix (mounted state)
- Defensive truncateCid for empty values
- CSP fix (template literal)
- Error boundaries (upload, profile, usage)
- 191 tests passing

next.config.ts

@@ -1,12 +1,15 @@
 import type { NextConfig } from 'next';
 
+// Haal de RPC URL op uit environment variabelen
+const zkSyncRpcUrl = process.env.NEXT_PUBLIC_ZKSYNC_RPC_URL || 'http://localhost:3050';
+
 const csp = [
   "default-src 'self'",
-  "script-src 'self' 'unsafe-eval' 'unsafe-inline'",    // nodig voor Next.js
+  "script-src 'self' 'unsafe-eval' 'unsafe-inline'",
   "style-src 'self' 'unsafe-inline'",
   "img-src 'self' data: blob: https://ipfs.maos.dedyn.io https://*.maos.dedyn.io",
   "media-src 'self' https://ipfs.maos.dedyn.io https://*.maos.dedyn.io",
-  "connect-src 'self' ws: wss: ${process.env.NEXT_PUBLIC_ZKSYNC_RPC_URL || 'http://localhost:3050'}",
+  `connect-src 'self' ws: wss: ${zkSyncRpcUrl}`,
   "frame-src 'self'",
   "base-uri 'self'",
   "form-action 'self'",