Add register + logout auth flows, and batch-5 resources

Auth (hand-built, uses the auth core):
- /register + register() action: validates, hashes with argon2id (hashPassword),
  creates an emulator-compatible users row (accountCreated/ipRegister/ipCurrent/
  look), redirect kept outside try so NEXT_REDIRECT propagates. Login/register
  cross-links; header shows Register (logged-out) and a Logout (signOut) button.

Batch 5 (parallel agents): /admin/rooms (+[id]) search+detail, /admin/vouchers
(CRUD), /admin/subscriptions (read), /admin/calendar (campaigns+rewards read),
/marketplace (public). Header + admin nav extended.

Verified: tsc exit 0, vitest 48/48, next build exit 0 (52 page routes).

src/components/site-header.tsx

@@ -1,5 +1,5 @@
 import Link from "next/link";
-import { auth } from "@/lib/auth";
+import { auth, signOut } from "@/lib/auth";
 import { prisma } from "@/lib/prisma";
 import { siteSettings } from "@/lib/services/site-settings";
 
@@ -48,6 +48,9 @@ export async function SiteHeader() {
           <Link className="nav-item" href="/shop">
             Shop
           </Link>
+          <Link className="nav-item" href="/marketplace">
+            Market
+          </Link>
           <Link className="nav-item" href="/community">
             Community
           </Link>
@@ -103,11 +106,26 @@ export async function SiteHeader() {
             <Link className="nav-item" href={`/u/${session.user.name}`}>
               {session.user.name}
             </Link>
+            <form
+              action={async () => {
+                "use server";
+                await signOut({ redirectTo: "/" });
+              }}
+            >
+              <button type="submit" className="btn btn-outline">
+                Logout
+              </button>
+            </form>
           </>
         ) : (
-          <Link className="btn btn-outline" href="/login">
-            Login
-          </Link>
+          <>
+            <Link className="nav-item" href="/register">
+              Register
+            </Link>
+            <Link className="btn btn-outline" href="/login">
+              Login
+            </Link>
+          </>
         )}
       </div>
     </header>