Upgrade to Next.js 16, enable SSR, update packages

- Upgrade all packages to latest versions
- Enable SSR (dynamic = 'force-dynamic') for all pages
- Update PostCSS config for Tailwind CSS v4 (@tailwindcss/postcss)
- Fix Edge-compatible CSRF token generation (Web Crypto API)
- Remove deprecated eslint config from next.config.ts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tsconfig.json

@@ -1,7 +1,11 @@
 {
   "compilerOptions": {
     "target": "ES2017",
-    "lib": ["dom", "dom.iterable", "esnext"],
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
     "allowJs": true,
     "skipLibCheck": true,
     "strict": true,
@@ -11,7 +15,7 @@
     "moduleResolution": "bundler",
     "resolveJsonModule": true,
     "isolatedModules": true,
-    "jsx": "preserve",
+    "jsx": "react-jsx",
     "incremental": true,
     "plugins": [
       {
@@ -19,14 +23,17 @@
       }
     ],
     "paths": {
-      "@/*": ["./src/*"]
+      "@/*": [
+        "./src/*"
+      ]
     }
   },
   "include": [
     "next-env.d.ts",
     "**/*.ts",
     "**/*.tsx",
-    ".next/types/**/*.ts"
+    ".next/types/**/*.ts",
+    ".next/dev/types/**/*.ts"
   ],
   "exclude": [
     "node_modules",