chore: migrate sign in to domain relative path with clerk, add .env.example as well

web/src/app/(app)/auth/sign-in/[[...sign-in]]/page.tsx

@@ -0,0 +1,9 @@
+import { SignIn } from "@clerk/nextjs";
+
+export default function Page() {
+  return (
+    <div className="w-full h-full items-center flex justify-center">
+      <SignIn />
+    </div>
+  );
+}

web/src/app/(app)/auth/sign-up/[[...sign-up]]/page.tsx

@@ -0,0 +1,9 @@
+import { SignUp } from "@clerk/nextjs";
+
+export default function Page() {
+  return (
+    <div className="w-full h-full items-center flex justify-center">
+      <SignUp />
+    </div>
+  );
+}