Refactor auth session handling and server actions across app

- Overhaul `lib/auth/server.ts` and `lib/auth/session.ts`; update all API
  routes and server actions to use the revised session pattern
- Refactor server actions (settings, titles, watchlist, setup) for
  consistency with new auth layer
- Extract `SetupForm` into its own client component with `useActionState`,
  animated steps, and copyable env snippets
- Move landing page redirect logic into `app/page.tsx`; slim down
  `LandingPage` component
- Add `proxy.ts` for local dev proxying
- Minor cleanup to `NavBar`, `MobileTabBar`, and `TitleCard`

proxy.ts

@@ -4,19 +4,21 @@ import { type NextRequest, NextResponse } from "next/server";
 const authRoutes = new Set(["/login", "/register", "/setup"]);
 
 export function proxy(request: NextRequest) {
-  const sessionCookie = getSessionCookie(request);
   const { pathname } = request.nextUrl;
 
+  // this is ONLY for optimistic redirects, it does not provide any actual security
+  const sessionCookie = getSessionCookie(request);
+
+  // Special case for root: becomes dashboard if logged in, landing page if not
   if (pathname === "/") {
-    if (sessionCookie) {
-      return NextResponse.rewrite(new URL("/dashboard", request.url));
-    }
-    return NextResponse.next();
+    return sessionCookie
+      ? NextResponse.rewrite(new URL("/dashboard", request.url))
+      : NextResponse.next();
   }
 
   // Logged-in users on auth pages → dashboard
   if (authRoutes.has(pathname) && sessionCookie) {
-    return NextResponse.redirect(new URL("/dashboard", request.url));
+    return NextResponse.redirect(new URL("/", request.url));
   }
 
   // Unauthenticated users on protected pages → login
@@ -29,13 +31,6 @@ export function proxy(request: NextRequest) {
 
 export const config = {
   matcher: [
-    "/",
-    "/login",
-    "/register",
-    "/dashboard",
-    "/explore",
-    "/settings",
-    "/setup",
-    "/titles/:path*",
+    "/((?!api|_next/static|_next/image|favicon.ico|sitemap.xml|robots.txt).*)",
   ],
 };