chore(app): move pages to locale segment

Move home, sign-in, and sign-up pages under app/[locale] for next-intl routing support.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/app/[locale]/page.tsx

@@ -1,5 +1,5 @@
 import { useTranslations } from "next-intl";
-import { ThemeChanger } from "../components/core/ThemeChanger";
+import { ThemeChanger } from "@/components/core/ThemeChanger";
 
 export default function Home() {
   const t = useTranslations("HomePage");

src/app/[locale]/sign-in/page.tsx

@@ -0,0 +1,20 @@
+import { AuthForm } from '@/components/auth/AuthForm';
+import { routes } from '@/lib/routes';
+
+type SignInPageProps = {
+  searchParams: Promise<{
+    callbackURL?: string | string[];
+  }>;
+};
+
+export default async function SignInPage({ searchParams }: SignInPageProps) {
+  const params = await searchParams;
+  const callbackURL = Array.isArray(params.callbackURL)
+    ? params.callbackURL[0]
+    : params.callbackURL;
+  const redirectPath = callbackURL?.startsWith('/')
+    ? callbackURL
+    : routes.private.dashboard;
+
+  return <AuthForm mode="sign-in" redirectPath={redirectPath} />;
+}

src/app/sign-in/page.tsx

@@ -1,5 +0,0 @@
-import { AuthForm } from '@/components/auth/AuthForm';
-
-export default function SignInPage() {
-  return <AuthForm mode="sign-in" />;
-}

src/app/sign-up/page.tsx

@@ -1,5 +0,0 @@
-import { AuthForm } from '@/components/auth/AuthForm';
-
-export default function SignUpPage() {
-  return <AuthForm mode="sign-up" />;
-}