feat(back-button): enhance button styles and add variant support; refactor back navigation in sidebar and coins rules screen

src/app/sidebar/sidebar-screen.tsx

@@ -4,13 +4,13 @@ import { LogOut } from "lucide-react";
 import { signOut } from "next-auth/react";
 import { useRouter } from "next/navigation";
 
+import { BackButton } from "@/app/_components";
 import { MobileShell } from "@/app/_components/core";
 import { ROUTES } from "@/router/routes";
 import { useAuthDispatch, useAuthState } from "@/stores/auth/auth-context";
 import { useUserDispatch, useUserState } from "@/stores/user/user-context";
 
 import {
-  BackBar,
   SidebarWalletCard,
   UserHeader,
   type SidebarUserState,
@@ -56,7 +56,7 @@ export function SidebarScreen() {
         <div className={styles.bgOrbTwo} aria-hidden="true" />
 
         <div className={styles.topBar}>
-          <BackBar />
+          <BackButton href={ROUTES.chat} variant="soft" />
         </div>
 
         <section className={`${styles.userSlot} ${styles.revealOne}`}>