feat: Implement Convex authentication including sign-in/sign-up UI, Convex client provider, and backend auth functions.

convex/auth.ts

@@ -0,0 +1,6 @@
+import { convexAuth } from "@convex-dev/auth/server";
+import { Password } from "@convex-dev/auth/providers/Password";
+
+export const { auth, signIn, signOut, store } = convexAuth({
+    providers: [Password],
+});