Implement waitlist landing page FRE-656

- Add waitlist tRPC router with signup mutation and count query
- Add referral code generation and tracking
- Register waitlist router in app router
- Add useWaitlistSignup, useWaitlistCount, useReferralCount hooks
- Update landing page with email capture form, live waitlist counter, referral sharing
- Add waitlist and referral CSS styles

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/lib/api/trpc-hooks.ts

@@ -324,3 +324,32 @@ export function useDeleteScene() {
     },
   }));
 }
+
+// Waitlist hooks
+export function useWaitlistSignup() {
+  return createMutation(() => ({
+    mutationFn: async (input: { email: string; name?: string; source?: string; referralCode?: string }) => {
+      return await trpc.waitlist.signup.mutate(input);
+    },
+  }));
+}
+
+export function useWaitlistCount() {
+  return createQuery(() => ({
+    queryKey: ['waitlistCount'],
+    queryFn: async () => {
+      return await trpc.waitlist.getCount.query(undefined);
+    },
+    refetchInterval: 30000,
+  }));
+}
+
+export function useReferralCount(referralCode: string) {
+  return createQuery(() => ({
+    queryKey: ['referralCount', referralCode],
+    queryFn: async () => {
+      return await trpc.waitlist.getReferralCount.query({ referralCode });
+    },
+    enabled: !!referralCode,
+  }));
+}